I doubt Nic would have chosen a coin for his daughter whose Fallen was categorically unwilling to treat their bearer as a partner and insisted on outright domination.
I was using it as a hypothetical example to explain that we had more interactions with hosts and not with fallen. The We have seen two fallen with different hosts, Ursiel and Magog. For Magog, through Sanya's reporting and by the one that Elder Gruff Killed on DR it seems that he prefers domination. It seemed that Ursiel prefered the same based on the interaction with him in Blood Rites (via Harry's Soul Gaze), but when interacting with the Geno in SG it seemed more interested in a partnership, or was at least unable to dominate the Geno.
Full ramps seem like a grey area. We're not really sure whether the soul entirely leaves the building when they turn (Susan remaining willing to be sacrificed suggests it's not instant). I'd gather the Fallen could probably bond with one in a pinch, but given how far they've already corrupted themselves, a rampire is probably less of a notch in their hellish bests to corrupt than a mortal human.
It may be slipping my mind, but I have not read the bigfoot shorts, but what exactly is the Geno, is he a fae, mytical creature or what? Cause he took a coin.