Nightcrawler would make sense because Aaron and McGuinness built "Amazing X-Men" around Nightcrawler's return and then left the book early due to the X-Men editorial craziness of 2014.

There's a long, long tradition of writers using the Avengers to tie up loose ends for their pet characters from books they left (or books that got cancelled, like Steve Englehart with the Beast's solo series).