"(Future plan: 'Will' will only be able to wear his own hat - wearing other hats will cause his sanity to drop.)" - You can try giving him a HUGE passive sanity degen, which is only offset by his own hat, to which you should give an equal amount of passive sanity regen, to the hat that is, so the two cancel out. Also i recommend giving Will a tag (e.g. "will") and having a check done when someone equips the hat if the person has this tag or not, and only giving the sanity buff if he is the guy. Also note that this solution gives Will an easy way of going insane and staying there.