1. It would not be able to be his specific servant. Though it isn't a playable character, we do ask that it not be one-of-a-kind creatures from canons, so the Bone Dragon would not be permissible. However, a generic skeletal dragon that's not that specific one would be fine (since undead dragons are a thing outside of his canon anyway.) It's kind of a weird situation where the creature is generic enough that the type could be claimed by anyone regardless of canon, it just wouldn't be able to be that specific one. (This has a lot to do with castmates-- if Character X claims Character Y's bff summon who he's also pals with, then it wouldn't make sense if Character Y also claimed it, and mods don't feel that it's fair to anyone to say who deserves it more especially in cases where we may not be 100% canon familiar. While it's more obvious in some cases, it's less obvious in others. So to be fair to everyone, we don't allow That Specific creature in canon and only generic versions as available.)

2. Mod contact or PM the mod account would be best, and only if it's something like notable, would have an effect on multiple people, or if it becomes prolific. We're not going to micromanage your villainy, but if it's something that would be noticed around town or with a lot of witnesses, we'd like to chat with you about it. Just hit us up on the mod contact page or PM the mod journal as the best way (we only check the plurk when we're posting news, so I don't recommend contacting us there unless you wanna wait until the next calendar deadline.)

3. Up to you! If you choose to have him come in with it, as you said, it would be dormant and purely there for aesthetics.