Pre-Arcadia:
Kinessa Jasmine Carter was born to a lower-middle class family. She was always intellectually curious as well as extremely driven in school, and eventually ended up attending a top tier university as a statistics major. Despite having good grades in an employable major from a good university she found herself totally unable to find a good job (for a lot of reasons, but the two primary ones were 1) she was a bit of an anti-social asshole who bombed interviews. 2) she was unreasonably picky about what job she was willing to take).
To try pay off her student loans, as well as other expenses she took up gambling. Not in the "I'm going to play slots because I'm so desperate and have no other options" way, but rather in a highly calculated way. She started with sports betting, with significant success due to rather rigorous statistical analysis, and later branched out to card games like poker and blackjack, employing strategies such as card counting to her advantage.
Eventually she had probably reached a point where she was actually semi-financially stable, if not completely debtless or comfortable. However she continued to gamble, making larger and larger bets, not because of a greed for money, but because she loved the adrenaline of risking a lot, as well as the pride/power of being able to win and take someone's money.
One day, she lost a game of Pinocle against a man with dark golden eyes, and in doing so lost her soul.
Arcadia:
Her Keeper, whom used the moniker The Countess of Cards (yes "Countess" despite appearing as a male figure), had a realm known as "The Betters' Haven", which was essentially Arcadian Vegas for hobs, as well as the occasional True Fae patron. The dealers, bookies, and other staff were all captured changelings. Obviously some the games the fae play, as well as the stakes they gamble with, could be quite senseless (to mortal understandings; they surely make perfect sense to the fae) and sometimes outright horrifying/sanity destroying.
When she wasn't helping run the casinos Kinessa (and the other changelings) would often be required to gamble with The Countess to entertain him. The stakes if she won were always the same: her freedom. If he won the stakes would change every time. Sometimes they would be relatively harmless, a lock of hair, or a song she must sing. Othertimes he might ask for more, an important memory or an entire limb.
She lost dozens, if not hundreds of these games before she eventually won. It was a game of pinocle, just like the one that got her into Arcadia in the first place. And thus, she won her freedom.
Back to the mortal realm:
The transition back to earth required a lot of adjustment for Kinessa. After spending years in a fairy casino, which would make mortal Vegas seem calm by comparison, the human world seemed so mundane and under-stimulating. She doesn't necessarily want to return to Faerie, and she is certainly no loyalist, but there are certainly nights where she wistfully dreams about some of the better parts of her durance. Though, on others she has nightmares about some of the horrific games, as well as the painful price she sometimes had to pay for losing.
To cope, she has continued to be deeply curious about everything. She is always striving to learn more, both about the supernatural and the mundane. She also will challenge anyone she can to a gamble, pretty much any game with any stakes. Her gambling addiction was only intensified by her durance.
Kinessa has a good heart. She will try help someone in need, especially if she knows/cares for them. She wants to see the world become a better place. However, her clarity is low, and she has a dark side; she will gleefully destroy someone's life by taking everything from them in a gamble, and she may refuse to help in even life-or-death situations unless the requester will play a game with her.
She has also grown deeply superstitious about fate and luck, basing most of her decisions on it and building a personal belief system all based on the forces of fate she believes in guiding the universe.