Hmm, I'm not 100% sure about the illness. That could lead onto not wanting to convert other people for fear of hurting them.

Although, in the last RP, those under William's control tended to change personalities to be more aggressive during the heat of battle, but were nice and friendly otherwise (Such as when they worked together), so I guess that's a possibility.

I'm thinking go for it. Sam could have it worse than everyone else, perhaps he had some sort of gene already in him that had the possibility of that happening, but it never surfaced as it wasn't complete. Perhaps the Lyoko Transfer will be just enough to do it... like how it made Garsin see. Sam might also become attached too his other personality, and not want to let him go, as it would be killing another living being.