This story is a sequel to Purple Clash- a Genetic Research story
Fluttershy travels to the Griffin Kingdom accompanied by Trixie, though Trixie might think it's the other way around.
Part six of the Genetic Research series. Start at the beginning here
sequel here
Hmm... the description is a bit misleading, since Flutters and Trixie don't actually reach the Griffon kingdom before the story's end.
The story was cute, though I think there was some wasted potential for humorous personality clashes. I think I just prefer my Trixie more over-the-top than yours.