In the very beginning of the series Debbie is described by Frank as being "sent from the gods." However, we soon learn that description is a bit of an exaggeration. Except not by much because she is extremely mature and grounded for her age. So much so that she has trouble relating and socializing with kids in her age group.
Throughout the Seasons
In Season 1, Debbie has a very kind heart and is very persistent. She takes Liam to school with her in the pilot since nobody can take care of him and she looks really hard to find Frank when he's missing in Canada in episode 2, "Frank the Plank". In episode 3, "Aunt Ginger" it is Debbie who cares for Aunt Ginger, who is really an elderly woman that Fiona and Frank borrowed from Veronica's nursing home. Following Ginger's return to the nursing home, Debbie steals little Casey Casden, a neighborhood boy who she takes after witnessing his father playing with him and his sister in their yard and she gets jealous. She is forced to return him to his home through a carefully devised plan to return him so nobody gets in trouble. She is a main pawn in the planning of Frank's fake funeral to outrun two men whom he owes $6,000, which is done successfully. Next, in "It's Time to Kill The Turtle", Debbie loves the new sober Frank, with whom she bonds with over sugar, which he uses to escape his need for alcohol in order to get $3,000 in a medical study. She's the one who ends up encouraging Lip and Fiona to "kill the turtle" as she put it, a misunderstanding to the reference that Lip had made about Frank previously. She decides to end his attempt at staying sober after he plans to slam holes in the roof through the attic for skylights with Carl. When Monica arrives home in episodes 9 and 10, she's initially reluctant to accept Monica's apology, but she eventually does, until she gets serious about taking Liam, which is when none of the kids support her apology if they ever did to begin with. In "Daddyz Girl" she signs Monica up for her classroom mom's group, but since she has once again left the children she convinces Fiona to go, where Fiona befriends Jasmine Hollander. It is Jasmine who drives Fiona and Debbie to the police station when Lip and Ian are arrested driving a car Jimmy leant them, and the two spend the night sleeping in the waiting room of the police station. She's the one who discovers Jimmy/Steve's double life, something she knows is wrong and pushes very strongly despite both Veronica and Sheila telling her she should leave Fiona to deal with her own relationships. Throughout most of the season, she is either looking into Jimmy's past, visiting his house, or harassing Jimmy about the lie he's living, frequently encouraging him to tell Fiona the truth about himself.
In Season 2, Debbie has grown up a bit. She's running a full-fledged daycare out of her home on her own, with the money she earns going into the winter Squirrel Fund. She ends up with a stress rash, which she attributes to being from melamine-tainted laundry soap she bought at the Dollar Store. In reaction to this, Fiona forces her to throw a party, at which she invites Simon, a boy who has a crush on her whom she only invites so he'll invite Holly Herkimer, a girl several years Debbie's senior who is still in Debbie's grade and is said to have HPV, in addition to Lip, Ian, Carl, and Carl's friend Little Hank, who she has a crush on throughout most of the season, her first real crush. She goes to Lip and asks him about what he liked about Karen, so she knew what to do to make Little Hank like her. His response was that it was about pheromones, so she dressed in Fiona's clothes and went to Mandy for help with makeup. Debbie also ends up obsessed with death after seeing the dead body of Aunt Ginger's boyfriend Harry at the end of episode 2 "Summer Loving". After this traumatic event, she ends up thinking about it constantly for a whole episode and doing a hilarious rendition of #1 Crush by Garbage. When Grammy Gallagher returns in Season 2, Debbie is more than happy to keep her secrets after being handed a $100 bribe, and when Monica returns Debbie is more than happy to side with her. She even sneaks into the hospital to help Frank break her out of the psych ward when she signs herself in for a period of time.
At one point during Season 3, Debbie expresses her desire to go swimming at the city pool. Frank tells her it's a bad idea because "at the city pool there are city kids." Apparently one summer, these city kids ripped Debbie's bathing suit to which she says they were just trying to make it into a bikini. Frank then tells her that if those kids will do that to her while running through the sprinklers in her own front yard, just imagine what they might do with an entire body of water at their disposal. Ultimately, Frank will not allow Debbie to go to the pool until she is able to hold her breath for ninety seconds, saying that if she can hold her breath that long that it will be long enough for her to get out of any trouble (should she ever find herself in it). Debbie soon is able to hold her breath for over one hundred seconds, ensuring her ability to swim at the city pool. However, the type of city kids she runs into are not what Frank was expecting, they come in the form of young pubescent girls with whom Debbie attends school. They tease her for her childish one-piece bathing suit, ask her if she's a lesbian, and tell her she should "grow some tits." The next time Debbie goes to the pool she sneaks a white bikini from Fiona's drawer and adds extra padding on top with some socks. She bravely goes for a dip in the pool, and she comes back to sit at her chair and read a book. However, this moment of bravery was short lived as someone put ketchup on the chair Debbie was sitting at, and the girls scream at her, "period! period!" and everyone laughs. A humiliated Debbie rushes home and locks herself in her room and sobs. Fiona tries to console her by telling her that,"nobody fucks with the Gallaghers." Debbie gets the courage to go back to the pool and this is where her ability to hold her breath pays off. She fills two bags with sand which she uses as a weight to hold her down. As one of the girls who humiliated her is about to get out of the pool, Debbie grabs onto her leg and holds her underwater until she passes out. She's quite happy with what she accomplished and runs back to the Gallagher house, screaming, "That's right! No one fucks with a Gallagher!"
In Season 4, having two friends who glamorize sexual promiscuity, Debbie meets Matt, a 20 year old at an arcade who she attempts to seduce only to have him reject her. Although upset, she agrees to only become friends. She finds out Matty has started to date a girl who works with him. She become jealous and tries to make the girl stay away from Matty by threatening her and putting a snake in her car. Later, she is confronted by Matty's apparent girlfriend who threatens her with a baseball bat to stay away from him. One day at school a boy in her class starts to show interest in her. He asks if they can dissect the frog together, she accepts but her friends who are interested in him want to work with him too. He shows her all the frog parts, Debbie is not grossed out but her friends are very disgusted. When he gets to the frogs heart he gives her it. Debbie is very flattered at this gesture. They hang out more that day at school and he even sketches a picture of her. He asks her if they can meet up after his basketball practice, she accepts. They then are making out and he takes off her shirt when suddenly a bunch of people pop up and laugh and take pictures of her. Matty's girlfriend is there and says that the boy that has seemed interested in Debbie is actually her step-brother and she paid him to do this. Debbie is shocked and majorly heartbroken. Matty finds out and breaks up with his girlfriend, he asks Debbie to remain friends. She accepts but is secretly more devoted than ever to get him back as her boyfriend. In season 5, Debbie invited Matty to a party where he got intoxicated after drinking Frank's booze and then coerced him to have sex with her.
In Season 5, Debbie launches in to the world of sex. Debbie has a party and when her friend Matt (who she always wanted to be more) passes out drunk she climbs in bed beside him and after seeing his boner puts a condom on it and has sex with him - which is technically rape but Matt won't do anything about it because it might back fire remember he is 21 at this stage. After Debbie gets into a fight with Holly and is saved by Derek she begins to show an interest in him. Debbie attends the gym that he goes to for boxing and keep fit classes and then he starts to hang out with her more and begin to like her in the same way, they begin a relationship together after Debbie creates a scene in front of the Gallagher household. Debbie meets Derek's family and she learns about this girl his parents look after who is a teen mom and intrigued by this, she also learns Derek's parents were childhood sweethearts and had a baby when they were not that much older than Derek and herself. Debbie then convinces Fiona that she should go on Birth Control while attending the clinic the nurse tells Debbie that if she is planning on having sex in the next few days she should still use a condom because the pill will not work until that long. That same day Debbie goes home and she is with Derek he goes to put on a condom before having sex she says "it's okay I'm on the pill" and they have sex. In the final episode of the season Debbie has an altercation with Fiona and she says she is pregnant. She tells Fiona she wanted to get pregnant and she knows who she loves and she knows what she wants.
Fiona hates this so she tries to convince Debbie to get an abortion. Fiona finds out she is pregnant too. Debbie is excited and says that they can raise them together. Fiona tells her that they can instead get abortions together and have babies when they are both ready. Debbie is outraged and storms off. She later goes to the clinic with Fiona but doesn't get an abortion and lies to Fiona telling her that she got one. Fiona finds out that she lied when Derek's parents come to the house to discuss the baby. Debbie believes Derek will stay with her but then Debbie finds out that Derek moved to Florida to live with his Grandparent's because he doesn't want to be a dad yet. Debbie continuously tries to contact Derek but he disconnects his phone preventing that from happening. She still decides to keep the baby. Fiona does not approve of Debbie having this baby and tells her she will not support her when she gives birth. Debbie decides she has to find a place for her and her baby to live. With the help of Frank she becomes a live in nanny for the couple since the mother was dying of cancer. Encouraged by Frank, she tries to seduce the husband of the dying woman so they won't fire her, he rejects her advances. Frank takes the dying woman to The Alibi to give Debbie some time to seduce the husband. There Frank finds out that the dying woman used to be a lesbian. Frank tells Debbie this and suggests that she try to seduce the dying woman. Debbie dislikes the idea but still spends time with the dying woman. One night Debbie is in her room when someone enters and gets into bed with her, Debbie thinking this is the husband says "I was hoping you'd come" when turning to see its actually the dying woman. Later on the dying woman finds out she isn't dying anymore and the cancer is almost gone from her body. Frank tells Debbie she must start sleeping with her or else she won't have anywhere to live. Debbie tries to sleep with her but then stops before anything happens telling the woman that she is actually 15 not 18 and she isn't a lesbian.
On the episode Grandma Queenie to the Rescue, Debbie is shopping at a baby store when she meets a man who asks her opinion on a gift he is buying his sister. She tells him her opinion. He tells her thanks and says his name is Larry. They then meet again that same day and he asks her out for lunch. While they are deciding what to get he starts moving his foot against her leg she then says "You know I'm pregnant right? 7 months" He tells her he is fine with it. After they are done their date it seems as if they are going to kiss but then he kisses her baby bump instead, Debbie looks confused by his action. The next day Debbie is going to her baby class when she sees Larry she asks him "How'd you know I'd be here?". He tells he didn't and is there with somebody else while pointing to another pregnant woman. Debbie is very confused and he tells her that he has a baby bump fetish, where he is attracted to baby bumps on women. Debbie is disgusted telling him that "she can't believe she fell for him" he tells her they can still date. Debbie asks what happens after she gives birth. Larry responds saying that they won't date anymore but they can be friends. She also finds out that he his dating several other pregnant women but she is his only 7-month-er. She says he is a sick person and leaves the class.
Grandma Queenie, Frank, Chuckie, and Debbie move to Queen's commune where Debbie gets her own birthing tent. However, living at the commune is not all that it is cracked up to be as Debbie goes into labor and discovers that the midwife had not delivered a child in over ten years. While labor progresses, Debbie gets more and more anxious and eventually her and Frank flee the commune back to Chicago. Debbie delivers her baby on the kitchen table in the Gallagher house. Debbie named her child Frances Harriett, Franny for short, after her father Frank. After the birth the EMT arrives and Debbie and Franny leave in the ambulance alone after Fiona tries to join. Debbie's
After her daughter was born, Debbie tries to prove that she does not need any help in raising Franny. Frank's crying disturbs everyone in the house. Fiona wants to help, but Debbie refuses any help or advice. Lip hypothesizes that Debbie may suffer from postpartum anxiety. She stays up all night with Franny and takes her to school too. Debbie realizes the struggles of being a teen mom when she is not allowed in class with Franny. Debbie's teacher tells her that she should go to the guidance counselor to see how to continue her studies at home and suggests next time to use a condom. After a disastrous day at school, Debbie finally lets Lip hold Franny at the bar when she goes pee. After another night of no sleep for the Gallagher family, Debbie is awake and perky offering to cook everyone eggs. Lip believes that she is going to have a major crash soon. Sure enough, while Debbie is feeding Franny and studying, she falls asleep and Franny falls onto the ground. At night Debbie is found hiding under the staircase while Franny is crying. Debbie professes to Sean and Fiona that she is a terrible mother and dropped Franny. She states that she cannot get Franny to stop crying and she cannot feed her enough. Fiona feels Debbie's head and tells her that she has clogged ducts and that warm water and ibuprofen will help out. Debbie reluctantly goes to Fiona's wedding to Sean stating that she wants Franny to be in the photos.
In season 7, Debbie is at a park with Franny and tries to talk to a fellow mother who sees that she's a teen mom and ignores Debbie. Debbie then turns around and steals the mother's luxury stroller and flips it on Craigslist, selling it for $1,500. With the money Debbie hires a night nurse to take care of Franny and begins to attend school again. This is short-lived after Debbie accidentally steals a stroller with a baby in it. After this point, Debbie begins to steal from clothing stores, stealing hundreds of dollars of baby and mommy clothing at a time. After a few successful rounds, Debbie is caught stealing and Fiona is called. Fiona gets Debbie out of the mess by saying that Debbie is "special". Debbie is incredibly insulted, but plays along in order to avoid jail. Fiona chastises Debbie for being so stupid and careless, claiming that she's not thinking of Franny, who now goes by Harry. Fiona tries to emphasize to Debbie that if she is caught doing this again Harry will be taken away from her and that in order for Debbie to be a good mother that she needs to be there for Harry. Fiona later lays down house law, by stating that everyone in the house, except for Liam, needs to contribute money in order to live in the Gallagher house and if no one wants to that she will sell the house and move to a smaller house. Debbie has to contribute more because of Harry's living expenses as well, Debbie fights that this is not fair, but concedes seeing she has no other place to live. She has great struggles making money since she is a teen mom without any form of graduation or classification. Seeing no alternatives, she asks Frank and Sevtlana. Frank advises her to take advantage of people's pity by begging on the streets, while Svetlana suggests to find a "weak, desperate man" who could provide for her. Her attempts at finding a partner and begging both fail miserably, while she does find a solution. Marriage with a brain damaged man she found in Fiona's diner, as he has an apartment and money.
Debbie is a sweet, spirited, smart, kind-hearted girl. She has deep trust and loyalty towards her family, though she tends to live out daydreams. She lived for years with the hope of having a good father in Frank, hoping he may one day change. She showed genuine concern and care for her father when no-one else did. Though, she is capable of unconditional love, she demanded love from Frank in return, only to disappointed by his selfish, uncaring nature. When asked if she ever wished Frank dead, she confirmed it. She never offended or hurt Frank, while Carl would help his brothers throw Frank in trash containers. Debbie has, or at least had, a great deal of respect, trust and love towards Fiona, who was her closest sibling and only sister. She always supported her in house and often took care of Liam. She is greatly mature as she could explain a confused Carl how lesbian sex works in season 1. She holds great resentment for her mother for leaving, even despises her. This is evident through Debbie, when she first saw Monica in several years, pushing her away and running home, as well as her attempts to take Liam and "start her own family". Though her hatred is lesser than Fiona's, due to Debbie's last days with Monica being of mostly positive nature. She loves Liam deeply, whom she spends most time with, and began to cry when Monica announced that she wanted to take Liam with her. Her relationship to Frank is very complicated. It shows her ability to daydream at her maximum when she tolerated him most, as well as doing little acts of kindness like putting a pillow under his head when he's passed out, or making him breakfast. She never receives more than a smile from him, and only when he's in his rare sober states. This frustrates her to the point where she stole a baby that had a father who plays with him out of envy. She prayed for his safe return when he disappeared and even posted pictures of him at their house's fence, or hugging him tight at his return. She tried to talk and play with him, even when he expresses open disinterest. Her love for her father ultimately died, when Frank destroyed her school project, calling it "a piece of shit". She had a frustrated rage in which she beat him with a bag of soap, screaming in sadness and frustration. Afterwards her relationship to him cooled down, once she finally understood that Frank will never change. Though, she continued to spend time with him, she lost most of care for him. When Carl said he would die, she simply shrugged it off. In her teenager years, she grew obsessed with boys and sex, probably an influence of living in a house hold with her extremely sexually active siblings, mainly Fiona. She has darker, manipulative sides to her personality spectrum as well, and lived out cynicism and frustration. Her first boyfriend refused to have sex with her due to difference in their age. During one night, when he was drunk, she took advantage of it and had her way with him. She expected him to be fancy with her afterwards, though it clearly contradicted his prior behavior. Her second boyfriend was in her age and they understood each other well, yet she drifted into a daydream again. She grew obsessed with creating her own "happy family" with him, the total opposite of her own family, she grew up with and started resent. She recklessly tricked Derek into making a baby with her, without asking his opinion or permission, or even knowing his own dreams and desires. This might be her most selfish act, as she casually changed the lives of them both, simply out of her own desire to have a family and expected everyone to simply play along. But she loves her daughter regardless of her unfulfilled dream, even if Franny means that she will have to live out an unsatisfied and unfulfilled existence because of her. She has great resentment for Derek for abbandoning her and destroying her delusional dreams, and shows little understanding for his personal motives, calling him a "deadbeat". Her relationship with Fiona is somewhat cold, as she lets her frustration out on Fiona, resenting her for "fucking them all up", as well as disliking her unsupporting nature since Franny's birth. One of her recently selfish deeds was finding her way into the life of a brain damaged man in order to live from him, though she claims to love his honest and simple nature. Not that she doesn’t care or nurture him, it’s just only that he can provide for her and Franny that she is together with him. During moving in in his appartement, she casually drives out a troubled family with little money, and shows no care for their bad living situation, showing her selfishness. Though her means and ways are somewhat questionable, she only wants the best for her loved ones, sometimes even going as far as harming others.