Francis, played by Christopher Masterson, is the oldest of the brothers and the biggest troublemaker. Francis is a regular character on the show for the first five seasons, although he has lived outside the house from the series' beginning. His mother, Lois, was in labor with Francis in the middle of her wedding to Hal. Francis was a troublemaker from a young age; he broke curfew, drank, smoked and slept around. Lois exiled him to a military academy after he was caught in bed with his girlfriend, and crashed the neighbor's car (which proceeded to burn up), and got 4 nose rings (Lois told him he would go to military academy if he got one nose piercing). From afar, Francis provides fodder for many subplots. Francis is shown (in frequent flashbacks) dating girls of which his parents did not approve, although he claims to be in love. He has been shown to be obsessive and going out of his way to prove Lois wrong (such as getting his nose pierced multiple times just in order to spite his mother who forbade him to do so).
Francis blames his mother for most of his problems and, at one point, even pretends to be an alcoholic in a ploy to make her feel guilty.
During the first two seasons, at the military academy, rebellious Francis finds a formidable adversary in Commandant Edwin Spangler, whose hook-for-a-hand proved a valuable comic device as Francis sows insurrection in the student ranks.In his time there it is shown that Franicis' vandalism at school is caused (at least in part) by his desire to stand up to Spangler after the Commandants cruel treatment of other cadets. After the second season, at only 17 years old, he legally emancipates himself with the help of forged signatures and an unscrupulous Alabama lawyer, infuriating Lois further as she was against him quitting school. He then leaves the academy, accidentally cutting off Spangler's remaining hand in the process, and heads to Alaska to work in the kitchen at a logging camp.
While in Alaska, he marries a local woman, Piama, whom he had dated for one month. Lois reacts hysterically and continues to be somewhat hostile toward Piama for some time. Piama, like Lois, is hot-tempered and does not shrink when Lois goes after her. By season 4 Francis and Piama have left Alaska (due to the closure of the logging camp) and Francis finds work as a farmhand at a New Mexico dude ranch owned by a German couple. Here, Francis becomes more of a responsible adult: he even begins to discipline his younger brothers, who always regarded him as a rule-breaking role model. A little over two years after he begins working at the ranch, however, he is fired because the ATM he used to deposit the ranch's funds was not actually an ATM.
For the remainder of seasons six and seven, Francis makes only occasional appearances, yet he is still credited in each episode. While visiting Francis, Dewey discovers that he has regressed and reverted to his old ways, living in a cheap apartment without getting a job. Here, he briefly takes a job as the manager for his friend's band and attempts to start his own business. In one episode, Francis got a job at a place for school activities and Dewey reveled in his new found freedom until they got to Dewey's school. He helps Dewey set things back in order by exposing Mr. Jeffers and Mr. Flerch for forcing his classmates into child labor by making lanyards in their own get rich quick scheme.
In the final episode, Francis and his mother fight over the fact that he remains unemployed. Later, his father discovers that Francis has been working at a large corporation called Amerisys Industries for two months. He explains that he enjoys his job of sitting in a tiny cubicle entering data into computers all day immensely, but he kept the job a secret from his family because he equally enjoys frustrating his mother by telling her that he is unemployed. Francis' final scene shows him taunting his mother over the phone with his non-existent unemployment by yelling, "You just can't stand that your son is still a free spirit!" He then picks up his briefcase, makes plans to come home right after work for dinner with Piama, kisses her, and happily heads to the office.
Francis is the most like his mother out of any of his brothers, which unfortunatly puts them at odds since he is the only one to blatantly stand up to her rather than go behind her back like the rest. Francis enjoys driving his mom crazy immensly but is completly willing to stand up for her should anyone else but him try anything.
Due to his childhood and the constant butting of heads with Lois he has developed a severe traumatic mother fixation, everything bad that happens and ever has happened in his life he automatically blames Lois for regardless of how minimal or non existant her connection to the situation is. It came to the stage that when Commandant Spangler asked him to name one thing wrong with his life that he didn't blame on her, to which Francis genuinly cannot answer.
Francis has a female counterpart in If Boys Were Girls named Frances. She is the eldest of four sisters and is followed by Renee, Mallory and Daisy. However, Frances like her male counterpart, has rebelled against Lois' wishes by quitting college to become a stripper and marrying men who had dead end jobs. As a result, she blamed all her problems and failed marriages on Lois, as she disapproved all of them. Frances is more closer to Hal and is the only parent she doesn't blame her problems on.