I'll tell you one person who I wouldn't mind seeing with a Coin just because it means the gloves can come off in dealing with him.......good ole Rudolph.
Hmm ... it's a long shot, but what if he already has been? H+K speculated he was being paid to stick the bank thing to them, but it didn't really fit with their previous theory he was on Marcone's payroll. What if Nic mailed him a coin after skipping town, and he's semi-possessed rather than bought? Maybe he's new enough not to be fully under the Fallen's thumb, but more or less as susceptible to mood and perception manipulation as Hannah Ascher was?
A fallen riding shotgun and torquing his mood and perceptions would explain a lot - the repeated loss of control, the apparently delusional take that Karrin had blown up a person rather than a jotun, and firing without seeming to mean to.
At first it seems weird that if he had a coin, he wouldn't have transformed when Harry was trying to kill him. But what if instigating Harry to murder him was the whole fallen plan? If Butters hadn't stopped him, he was on the verge of doing something that would have stained him as a warlock, submerged him into the winter knight mantle, and possibly even corrupted his access to soulfire (based on the smell of brimstone when Butters cut him). Could be Rudolph as a host, especially a not fully compliant one, wouldn't have been enough to take Harry out in an open fight. But tricking him into corrupting himself with a wrathful murder, with good odds Uriel would cut him loose and the Council might take him out? That's a good trade for one dixie cup bearer.
