This might not be any help at all and if not that is totally fine baha buuuuut if it is any use too you I have:

Kohl: Dark hunter who actually specializes in manufacturing weapons that DONT kill supernaturals but just disable them in a variety of ways as he has a no-kill policy so he might be useful in some fashion lol. I dont think he would agree to enslaving them but you could easily just not tell him what the weapons were for baha.

or

Frost: If only because I think Frost would find his business plans extremely intriguing and would potentially even help him if there was something in it for him, if Drago is not the type to engage in conversation with a horse though I totally understand baha. Frost would otherwise make a very, very poor slave and is thusly not useful for that side of the plan, but hey XD

If they are of no use to you that is totally fine but if you need any extra people for whatever reason I can throw one of them at you haha