Board Thread:Show-Related Questions and Answers/@comment-24214505-20140704165951/@comment-4839682-20140704202657

He doesn't need to have some personal conflict to be on the show. We saw him in flashbacks in "The Doctor", after all...

The Hatter is a realm-jumper, he's a well traveled man, and that kind of thing is useful, both in the present and in flashbacks. Or can be.

I would say the bigger issue is Sebastian Stan's schedule :)