Hey I've been thinking, any large gathering or location frequently occupied by many supernaturals always needs a secret hidden sect or organisation that governs over the actions and secrecy of its types. Sort of ruling, controlling and punishing those that misbehave...

I'm gonna make one such party of people residents of the big apple. Dorian as a new hunter in NewYork will pay them the pleasantries and formalities of one using their territory.
Those old enough and wise enough to have encountered his type before know to fear him regardless how much they dislike his presence and often try cur favour in the event their own name is on his list.

While it can be a socially testing, awkward and a bit of a 'mine is bigger than yours' event with hidden venomous words and accusations covered in false pleasantries, the whole ordeal is somewhat necessary. 
In the long run the formalities are a necessity to ensure minimal disruptions for the long term occupancy. And if he does happen to kill someone important to them they just might forgo the witch hunt.

So, there could be another fancy masquerade ball coming up!!!

This would be a good place to introduce your 2nd character (NPC)

[hider=caution, spillage of juicy sauce]


Just throwing this out there, not sure if you have a personality in mind, but...
Dorian hasn't always been the controlling, perfectionist neat-freak he is now. He may have had some hints of those traits but he was a different man before he met... Her.

After he lost seemingly everything, Dorian was a self destructive angry alcoholic. His methods of work were sloppy at best and I'll conceived.
There was a club or a bar that he frequented often, owned by a woman. And that's exactly what she was, a proud powerful sexy woman. A woman who seduced and toyed with the wrecked flesh shell that was Dorian. This woman besides owning the club, having exquisite tastes and being a full blown dominatrix was also a cleaner/reaper like Dorian. 
She taught him the sophistication, art and pleasure of the job/game. Dorian also found the guilt washing pain he had been so desperately searching for.
She reintroduced him into catering and servitude, rebuilt his longing for control and tantalizingly teased his every desire. Unbeknowingly rebuilding his powerful will along the way.
Only after she grew a man out of his defiance did she suddenly vanish, a fickle leaf upon a bustling breeze, only to occasionally come down to brush past his path if for only but a night, vanishing again with the slightest wind.

[hider=Sauce overload, trigger, 18+ warning. Dorians weakness.]
With a wikid grin, excited eyes and a devilish tongue running across her bloody red lips she says in a snide sexual humor, "so you finally took my advice." She slips in a dramatic pause between her words as she lets her nails run down his chest and those luscious lips slowly near his ear, in an ice cold tone she whispers.
"[i]so you're gonna fuck her before you kill her, mind if I join?[/i]"

Dorian could never tell when she was serious or teasing but her words held a long dormant power over him.

"It's quite a lucky score, getting to release one of your soulmates. I've only ever done it twice." 

To have killed two of her soulmates was an indication of just how many names had come across her wrist and gone. For the chance of one coming up at all seemed impossible up until now. At least in all his years Dorian had never heard of it.[/hider]ahh it wasn't that bad in the end :p [/hider]