In the last episode, Mark plans to propose to Sophie but changes his mind upon realising that they have nothing in common.
Nonetheless he ends up agreeing to marry her to avoid "embarrassment" after she accidentally finds his engagement ring and accepts a proposal which he has not actually made.
In the first series, Mark and Jez start out with similar aims of bedding their next-door neighbour Toni (Elizabeth Marmur), which Jeremy does - whilst she is separating from her husband, Tony.
They also launch a pepper spray attack on Super Hans, who has begun a fling with Toni.
Mark sees a therapist, and nearly succeeds in having sex with Sophie, but this chance is ruined by Jez's apparent overdose.
However, realising he was trying to get out of marrying her by hiding, she runs out on him after the ceremony, planning to seek a divorce or annulment because Mark is "horrible".
Much of series 5 revolves around Mark's search for "the one".
Mark and Jeremy spend a weekend on a canal boat for Mark's stag do, where Mark meets a businessman with contacts in India and attempts to secure a job there as a means of escaping his impending wedding.
However, the plan falls apart when Jeremy accidentally kills the businessman's daughter's beloved dog and attempts to avoid her finding out by eating the remnants of the dog.
Sophie leaves on a foreign business trip, leaving Mark to consider a fling with a woman who he recently met at his school reunion.
Jeremy finds some highly paid work as a handyman for 'The Orgazoid', one of his musical heroes - but discovers that his new employer expects Jeremy to give him "a hand".
Meanwhile, Jeremy's efforts to get back together with Suze are hindered somewhat by Super Hans' attempts to go cold turkey.
During series 4, Mark and Sophie visit Sophie's parents after their engagement, and Jeremy has sex with Sophie's mother.
Mark has a one-night stand with a teenage goth girl.