Vexen really isn't as bad as he tries to act. Just gotta get him to get attached, which Roxas is good at even if he doesn't do it intentionally. Adding a mess just makes it more fun.

Oooh the Yaksha thing might be fun since there's no set Cryo one for the five guardians. Though there would def be one that might have been a minor Yaksha we just never got story for. The karmic energy could play into that since it does seem to affect what they draw in. So even if he wants to fix his condition so he can become a better exorcist, he just has to live with it and could learn how to actually use it to his advantage.