The Banished or The Exiled, are terms used to describe True Fae who have been cast out of Arcadia by their fellows. Though their powers are lessened, most are still more than a match for all but the mightiest changelings.
Sometimes, the human world houses True Fae who can’t return to Arcadia. These Charlatans become less powerful, and without their links to Arcadia, they are effectively mortal. The True Fae that have been banished to the mortal world are among the rarest of Charlatans, but there isn’t a single one of them who doesn’t want to go right back into Faerie.
Some of the Banished were kicked out, sentenced to mortality by some Arcadian court. It’s difficult to imagine what could make a Fae anathema to his own. This may happen due to a broken Contract, but certainly some have committed other crimes so bizarre and alien, that humans or changelings couldn’t ever understand them, even if they were clearly explained in detail and illustrated with pictures. Others make the mistake of becoming diseased, infected by contact with mortals.
In Arcadia, everything is permissible, as long as it’s entertaining. A Fae can become attached to a mortal, but actually falling in love, actually taking that seriously? That’s not fun anymore. A Fae could wish revenge on some changeling, but if it becomes so important to the Gentry that it stops being diverting, then the Fae becomes a bore. The concepts of true love, true hate or any true emotion, are human concepts, and can only really be experienced by a being with a soul. The Others have no souls, but sometimes the emotion obsesses them. They become a little less Fae, infected with a false kind of humanity that they don’t understand. A being like this is dangerous to the Gentry, and dangerous to the human world.
Banished Fae remember their true identities, and unless forgetfulness is part of the curse that banishes them, they remember everything about Faerie and the circumstances that led them to the mortal world, but have been stripped of much of their power and are, for all intents and purposes, at the mercy of the human world. This makes them dangerous and bitter. Barred from Faerie, most of them become obsessed about returning. They desperately need that point of escape. The irony is that in the action of needing, in that obsession, the desire that overrides everything else, they become less and less able to re-enter Arcadia. It’s deadly serious for them, and that simple fact, more than anything else, is what keeps them excluded from Faerie forever - and it’s what makes them so terribly, terribly dangerous.