Actually, there is a plot device. A pretty big one. The Autumn Court is pretty well hidden from mortal and magical memory (we're still working out the details), but basically it involved a powerful working that caused them to disappear into the gaps between. They're still there and are even signatories of the Unseelie Accords (with a smudged, illegible signature), it's just any reference to them tends to become unclear. They've stayed out of things for a while now, and only now are starting to make waves because of perceived weakness in the main players.
In fitting with this, the character DID accept it, but only through faerie trickery. Long story short, she basically said "I wish!" in front of a genie. I don't think it's outside their standard modus operandi for the fae to take you at your literal word, even if you did not mean it or understand what you just agreed to. She was willing to write it off as something slipped in her drink or a bad fever. Until all the other weird stuff started happening.
And yep, even the Mark is frustratingly unclear. Mark of Power tells anyone who looks at the Knight "This person is claimed by *coughcough* and is a due representative of the interests of *muttered*. Treat them with all the respect you would *car alarm goes off*, or face the wrath of *look! A monkey!*"
I'm sure we'll fill in most of the details once we actually start play (we meet for city/character building tomorrow, I've just met with some players separately). I'm just wondering how the inevitable Council encounter would play out, whether it comes up in play or in character building.