Danny Boyle never thought he'd ever make a sequel to any of his movies.
The 'T2: Trainspotting' filmmaker admitted he changed his stance when he saw how fondly audiences still looked back on 'Trainspotting' and really connected with the likes of Ewan McGregor's Mark Renton, Johnny Lee Miller's Sick Boy, and Robert Carlyle's Begbie.
He said: "I can't say I [thought I'd make any sequels]. Even when we were talking about it.
"But one of the big reasons is I'd just run into people and hear the way they talk about characters. They still remember their names. When does that happen?
"I can't remember Jennifer Lawrence's character's name in 'Passengers' and I saw that yesterday."
Danny knew that in order to tempt back the main cast, which also includes Ewen Bremner as Spud, for the sequel, the concept for film had to hinge on treating their characters "equally" - but wasn't a "bad" plot.
He told the Los Angeles Times newspaper: "I think they were all fine in theory. In practice, I knew if the script didn't deal with them equally, like the first one, they wouldn't do it.
"So then we had to come up with a movie that did that and also wasn't...bad."
And another thing he had to be sensitive to was how the actors themselves have aged in the two decades since the original film.
He said: "Then there's the prism of aging, which is terrifying for a lot of us but really terrifying for actors. You remember them frozen in time and suddenly they're in the present."