Well, since I already made a Khornate daemonette and I'm probably a heretic who goes against the canon, I suppose there is no reason to stop there.

Kya used to be a Slaaneshi daemonette, devoted to excess, as most of her kind. After drowning herself in pleasure for millennia, she found a new obsession in knowledge and power, which made her abandon Slaanesh and join Tzeentch's cult.

Over the passing of centuries, the Changer of Ways altered her body, making her look like a daemonette-blue horror hybrid. She studied every magic lore as her new excess, learning almost every single spell known to mortals and daemons. After she learned everything, and that was left for her was emptiness and a sense of void and boredom.

Now Kya lives in a small Imperial town near Reikland’s border. She doesn’t bother to hide her daemonic nature, since the citizens can’t get rid of her anyway. The townsfolk have resigned themselves to her presence, and witch hunters no longer consider her worth the effort, considering she always ends up returning every time they send her back to the Realms of Chaos. Any trouble she might cause is probably an accident, anyway. The Winds of Magic tend to be agitated around her, and sometimes her warpfire ends up burning something (or someone).

Kya spends her days leading a mundane life among humans, going through routines with little interest in the war between Order and Chaos.