Why did Renton come home?

He was getting divorced and was about to lose his job, but he didn't really have a reason to come back.

His mum had died too.

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It's actually a really good question. The script is so poor that Renton never really gives a convincing reason. People will say 'oh because he collapsed' or 'oh, he's having a divorce' - but that doesn't answer the question, does it? What was he trying to achieve coming back? Who knows. Probably the only true answer is that ... he was coming back to be in the sequel of Trainspotting.

He had a severe case of nostalgia and regret/ remorse after having a near death experience with his heart, plus with all the other things happening in his life he decided to head back home and try and make amends with the lifelong friends he abandoned and his father.

It's clear that after experiencing a near death experience he decides to return home. To the only place he can know to be like home. Losing his wife makes him question what he's doing with his life and where it's actually taking him. Going home creates comfort in something he knows!

Because he fell off a treadmill and could not live with the shame.

Was probably on the Dutch equivalent of Harry Hills TV Blopers

Home draws you back when things all go to *beep*