User blog comment:Baluar/I'll be doing MY crossover, too/@comment-1419424-20150728043704

If you wait, I'll have a chapter or two of Will's fic up at some point (To You, If You Might Find This was an epilogue of sorts), probably in between finishing Arc 2 of GE:U and starting Arc 3. That should give him enough characterization and backstory to make him workable.