Harry Dresden, wizard and PI, had been surprised when Sanya came asking for his help. Apparently he had a feeling he was needed somewhere, and it would help bringing him along.
They arrived at the origin of Sanya's feeling to find a relatively quiet road (for Chicago) where they could see that people passing by often stopped as if to pick up something, then left, looking frustrated and often a little worried or surprised.
When they went to see they found an old, tarnished silver coin, a roman denarius, and they were both pretty certain it was that of one of the Denarians.
When Sanya tried picking it up, using a handkerchief to avoid touching it, he discovered it was stuck to the ground.
While Sanya considered how to get the Denarius up without attracting attention Harry looked around, to see if there was anything else unusual, and noticed a man standing still not very far from the coin, who seemed to be looking at them, or perhaps the Denarius, and went to talk to him.
His instincts were busy telling him the "man" wasn't human at all, and to be very cautious, mayne even stay away, but he decided to ignore them. "So, were you the one who stuck that Denarian to the ground?" "Oh, yes, serves the bastard well, he's probably getting quite the headache right now" "Why?" "Well... you know how touching one of those without picking it up gives you a copy of the actual fallen angel in the head? They only have one copy, so if someone else touches it afterwards the copy moves over to them, after first dumping their memories of the first person's mind in Varthiel's mind, now what do you think it's like for him now?" It wasn't exactly what he meant to ask (he wanted to know why the other had stuck a denarian to the pavement, not why the Denarian would get a headache) but having some experience with Denarians himself he could see why someone might want to give one of them a headache, even enjoy it. There didnt seem to be any haste, so he decided he might as well wait a little, enjoy thinking about how the fallen angel might be feeling, not before asking "Isn't it a little dangerous? What if someone manage to pick it up?" He got a look that said clearly the other one thought he was an idiot "If there was any risk of that I wouldn't be doing it, that coin won't get loose unless I want it too, besides Varthiel might be powerful, but he isn't particularly bright, even for an angel, most of those people are probably wondering why they thought they heard a voice saying 'Pick me up!Pick me up! Pick me up!' or something like that, by the way, can you tell your friend to move? He's keeping people away from the denarius, I promise I'll give it to you once I've finished".
Crowley, as the man had introduced himself, finally decided it had been going on for long enough, probably helped in reaching this conclusion by Sanya's disapproving frown, and so walked over, and picked up the Denarius, with no apparent difficulties, then handed it over to Sanya, who wrapped it up and put it away.
"How did you manage to just give it away like that? Didn't he try to control you?" "Oh, please, I might not be the most powerful of the fallen angels, but I'm not stuck in a coin, and this is my body, so I have the advantage of the terrain, so to say".
Having said that he left, leaving a stupefied wizard and an equally stupefied Knight of the Cross behind.