I think it would be interesting to see Karel of Fire Emblem 7 with Krystal of Starfox Adventures. Why? I thought up this pairing to scare the Krystal fanboys and add to the fact that Karel did'nt really had any female hook-up options in Fire Emblem with the exception of his own family, who end up with someone else. Sure this may sound like a strange idea for a crossover, but I think it could work out well, Krystal would use her telepathic powers to redeem Karel and help him remember his past, and also to calm him down so he won't kill his own allies.

I might write a collection of worksafe short stories featuring Nintendo characters and possibly based on the Super Smash Brothers universe. Most of them are action-oriented. One of these stories is where team Starfox seperate for a little while to take little vacations to worlds from other games to visit some good friends, which Krystal herself travels to Sacae, in Elibe, a continent in Fire Emblem, to visit a friend of her's, Karel, who quits his killing spree and now lives in a peaceful village, decides to spend some time with Krystal while she is visiting him.

It all makes sense, Karel x Krystal would still work as much as any other Nintendo crossover pairing.