[quote=@kapuchu]
[@Lugubrious]
Damn, no edgy emo teenager to do deals with xP 

That being said, the next obvious question is: Could Player Characters do it? Like Blair or Lily? Both seem to be in the "Intelligence" department of Hell (Sorry Fenn). DMC wiki does state that only certain powerful demons can take on human forms, and since both Blair and Lily have human forms... Is it the same minimum requirement, so to speak, or does the "Demon Contract" require a more powerful demon than even that? 
[/quote]

Human form is a sort of restraint on power.  Only powerful demons can do it for the sake of stealth and deception, I imagine.  Still, I imagine that they could.

Keep in mind we're doing contracts the Bayonetta way: it's not 'a demon agrees to do x and whatever x is happens if the human pays up.'  In Bayonetta, the contracted demons are physically at the contractor's beck and call.  Bayonetta summons her demons physically to the battlefield, through portals, to attack.  Humans less powerful than her would have less control over their demons, but still, it's not terrible advantageous for demons, so there's not really a good reason to do so.