Francis "Frank" Gallagher is the dad of the six smart, spirited, independent kids who, without him would be... perhaps better off!
A hopeless alcoholic and troublemaker, Frank is usually shown passed out drunk on the floors around the house when he's not at the bar spending what little money the family has. Frank is careless, selfish and completely narcissistic as he hasn't done anything in his life but collect disability checks and get intoxicated. He is also abusive, conniving, and in Lip's words, a "total fucking asshole." He provides next to nothing in the way of parenting or financial support and usually serves as one of the main headaches in the Gallagher household. Frank has also shown that he would give up his own children if it meant he can get booze (or money to get booze). His mother Peggy is the reason he is turned out so terrible. Frank is possibly a twin, however this claim has not been confirmed in the series.
Despite having a higher than average intelligence, the people in Frank’s life regard him as nothing more than a rambling drunk put there for either their amusement or aggravation (depending on the day). This often includes his children who spend a more than normal amount of time cleaning up whatever mess Frank has thrown himself into at the moment.
He has been transported to Canada and tried to convince the authorities that he is a citizen of the United States after two old joggers reported him even though he did nothing.
Frank has also tried to get $3000 from a hospital study to abstain from alcohol for two weeks, which he failed to do. Frank even asked Sheila to entertain him in the mean time. The children are surprised that he could be a great father when he is sober, but Lip advised Carl and Debbie to "enjoy the moment while it lasts." Frank's soberness becomes too much for the elder children when he tries to break a supporting wall with Carl. He loses his chance at getting the money when Lip and Fiona, spurred by Debbie, force him to drink alcohol. When Debbie returns home later that day, she sees a drunken Frank sitting on the couch watching a TV show about politics. After he allegedly had intercourse with Karen it is later revealed that no penetration actually occurred. Frank ask Lip for an apology to which Lip responds by urinating on him from his window. Without saying another word, Frank walks away, both unknowingly sharing a smile.
Child Protective Services
Frank calls Child Services at the Alibi in an attempt to get back into the Gallagher house, as he has been kicked out by Fiona. In the episode "The Sins of My Caretaker" an Asian woman is hesitating to go into the Gallagher house. A bloody Mickey is seen being carried into the house from getting shot at a failed robbery attempt. Fiona walks in when she hears Mickey screaming in agony as Dr. Lishman is removing a bullet from his buttocks in the kitchen. The daycare is out of order and Debbie, wearing a bathing suit walks in excited about her growing up moment at the pool. Fiona is surprised to see an unknown woman in the house and asks who she is. The Asian woman replies that she is with CPS. Much to Fiona's surprise and dismay, she later finds out that Frank had called child services. When she searches for the rest of the Gallaghers to see what homes they were placed in, she eventually convinces Frank to participate in a parenting class. In exchange, Frank asks for a free room back at the house and Fiona agrees. She at first looks for Monica. She calls her grandmother, Monica's mother, who apparently didn't remember her own daughter, but failed to find her and resorted to Sheila with the help of Frank. Sheila was again bothered that Frank showed up again to her house but agreed. Fiona asked the social worker who contacted CPS on her family to which the worker reluctantly allowed her to listen in secret due to violation rules. Fiona hears the tape and recognizes Frank's voice.
Afterwards, Fiona moves to file suit and convince the courts to terminate Frank's parental rights. A custody fight in court gave Fiona the position of legal guardian of the Gallagher children. As a result, Frank has been kicked out of his home and finds himself sleeping on the subway and fighting with homeless men. Eventually, he runs into Carl, who sneaks him in the truck in the backyard. After a moment with Carl that night, Frank and Carl come up with a plan to steal from Carl's previous foster parents. Carl gets caught but Frank takes the fall for his son getting arrested claiming it was him who stole. As a result, Frank is charged with theft and arrested by police.
While in prison, Frank's alcoholism begins to catch up with him as he can barely stand as his body and health begins to deteriorate. He tries to spent time with Lip when he runs into him at The Alibi Room where the two challenge each other on doing push-ups. Later after being released from custody, Frank joins Lip for a steak dinner and a skate at the park. It was there when Frank is rushed to the hospital after falling down unconscious and vomiting blood. Fiona visits him in the hospital denying Carl and Debbie access. After she tells Lip to go home, she sits down and talks with Frank. Fiona tells Frank that she would have preferred that he died since the thing she fears the most about Frank is him not caring for his own kids. Fiona then informs Frank how much her and the rest of the kids love him and want him to change. Carl visits Frank at the hospital and shaves his head, as it's presumed Frank may have cancer. Eventually Frank decides to get out of bed and walks out of the hospital and on to the streets. He walks alone alongside an empty bridge as the winter snow begins to fall.
Frank's liver fails, leaving him to make a life-changing decision to either find a donor or live out his last days. Frank's health is declining and he's becoming too ill to take care of himself. It's revealed that Fiona has allowed Frank back to live in the Gallagher house. Meanwhile, Frank tracks down his unknown first daughter, now a grown adult with a successful career and a kid of her own. Although she is not a match for his liver, she continues to care for him by buying drugs for his pain and making him comfortable as he appears to be near death. When Sheila returns from the Indian reservation, Sheila marries the unconscious Frank in an attempt to adopt several Indian children. At the middle of the season, Frank is finally granted a liver from a donor and gets his life saved. After being released from the hospital and successfully getting a new liver, Frank is wheeled out by Carl along the Chicago waterfront where Frank takes out a can of beer and victoriously rejoices about surviving and still being able to drink.