Then Josh asks nodding his head at Chomper.
Josh: So tell us how did you make friends with a T-rex?
Littlefoot: Well it's quite a long story. But we found him as an egg and hatched him and tought him to be a nice Sharptooth. Until his parents came looking for him.
Chomper: But I really missed Littlefoot and the others so I then came back to stay for a while.
Littlefoot: It was really hard to get everyone in the great valley to let him stay and convince them he was a friendly Sharptooth.
Cera: Yeah especially my dad. He made a huge fuss over it.
Littlefoot: But in the end they let him stay.
Chomper: Yeah I stay in a cave near the edge of the great valley.
Josh: Great valley, so that's what this place is called?
Littlefoot: Yes it's were all leaf eaters live and are safe from grown up Sharpteeth.
Olivia: Well It's very beautiful here, I certianly feel safe here now.
Yeah there's my explanation to why Chomper is here in this fan fic.
Also if your wondering, this is only in cannon with the first 4 LBT films. As those are the only ones I like as well as the 7th. Then you can say the back story to why Chomper is back was a sort of alternative version of the 5th film. Which is why he's still in his origanl 2nd movie design. And I went with that design as I like that one most.

Littlefoot: Well now we all know each other, do you want to play with us?
Josh: Oh yeah sure!
Olivia: Oh yes that would be a lot of fun.
Tom: But Josh what about that wired hole we went through, we don't know how long it will stay open for.
Josh: I know about that, but this is a ones in a life time chance to have fun with dinosaurs Tom. Our most favourite things.
Tom: Yeah your right, I guess we could stay a little while.
And so the 4 humans and 6 little dinosaurs go off to play in the great valley.