I'm pretty sure they wanted to leave that open-ended. That's how I saw it, at least. My guess would be that Paul takes some kind of position on the staff because I don't think he'd EVER agree to become a doll, even to save 'Mellie'.

Yeah, you're probably right on the creep-factor. Boyd's feelings for Echo are innocent and based an actual experiences with her whereas Paul's obsession comes only from what he knows about 'Caroline' and leans toward the attraction side.