"I mean, if you have torrents of all-purpose magic and therefore a better solution than killing him, be my guest, but he's a Class One vampire and therefore pretty much impossible for people in my universe to keep contained.
...Pen says you have vampires that are different from my kind. We have thirteen classes of vampire. Class One vampires--like me, or my wife, or this villain--are extremely fast, extremely strong, and heal from most injuries in seconds. Human prisons don't hold us if we don't want them to."