I saw this film quite a while back, like 6+ years

I’ts an animated film that starts in a fantasy world with 3 main characters, I think 2 boys and a girl. They do some things and then the writer of the fantasy world gets abducted in the real world, which causes the 3 main characters to be transported to the real world aswell.

then there’s a whole lot that happens but in the later part of the movie the 3 main characters go and rescue the writer in which they are succesful. 2 of the characters go back home but 1 stays behind either becouse he was forced to (becouse they had to hold open the portal) or becouse he decided he wanted to stay in that world where he had free will. yeah that’s another thing, they really emphasised that in the real world they had free will as opose to their fantasy world where there lives were written for them. kind of like a red pill blue pill situation. the movie was in colour. please help me find this film, I really liked it