Roy is a work-shy Irish IT technician and geek who spends much of his time playing video games or reading comics in the office.
[f] The series 4 episodes reveal Roy to have globophobia (fear of balloons)[g][5] and being extremely uncomfortable when a masseur planted a kiss on his bottom.
[h] Roy's family do not appear in the series, but in the episode "Aunt Irma Visits", he finds the resemblance of Moss's psychiatrist to his own mother disturbing.
Linehan said he originally thought the role should not be played by an Irish person, but that O'Dowd was the best man for the job, especially appreciating his physical performances.
[9] The humour in his character is derived from his socially awkward comments and his complex and in-depth knowledge of specialised technical subjects, including chemistry and electronic engineering.
Moss has some quirky habits: He switches through glasses of various sizes in reaction when he and Roy scheme; when his ears get hot, he sprays them with a bottle;[a][9] he uses inhalers;[k] he can detect chemicals such as rohypnol by smell.
[d] He suppresses his urges to cuss and does not like to break the rules, with an exception in the "Bad Boys" episode when he and Roy ditch work after lunch and he gets in trouble for shoplifting, consequently having to do three hours of community service and give a Scared Straight!
[g] In "The IT Crowd Manual", Linehan said that Moss was an amalgam of various stereotypes with some uniqueness brought together by him and Ayoade, and described him as a really nerdy guy and a geek.
[8] Jen becomes the relationship manager of the IT department, having been assigned by Denholm at the start of the series because she had impressed the latter by listing computers on her curriculum vitae.
[p][11] She becomes obsessed by pursuits such as buying cute shoes even though they are far too small for her feet,[k] and trying to impress good-looking men,[f][c] but her attempts to start relationships turn out to be disastrous.
[8] In series 2, Jen reveals that she was a heavy smoker several years prior; she briefly takes up the habit again, but quits when she realises the anti-smoking regulations have made her more socially isolated.
[l] As part of the subsequent sexual harassment settlement, he was required to wear "electric sex pants" that deliver shocks whenever he is aroused at work, although Moss disarms them later.
[h][15] He occasionally brings up the topic of denying having killed his first wife Melissa, and in the series 4 finale, he reunites with ex-wife Victoria for two weeks before they break up and he is sued for a large sum of money.
[17][8] In "The IT Crowd Manual", Berry described Douglas as so confident and privileged that he did not care where things would come out wrong, cause offence, or make him look like a fool.
[b][18] Richmond's absence from series 3 is explained as him having scurvy,[r] but Linehan noted in an episode commentary that Fielding was too busy on other projects.