Nightshade

Theta has taken his love of felines a step further than his fellow Cheshires by actually adopting a cat as a pet. A decent amount of understanding exists between the two and they often stroll the streets together (at Theta's request). Theta ensures the cat is taken care of if she is at all in danger of not being able to care for herself. That said, they fight about as much as the 'strolling through the streets together' dynamic can take - most of the time about the fine detail that Theta is taking chunks out of his cat's territory.

(P.S. don't assume that just because he’s nice to a cat he has any capacity for empathy toward humans.)

Theta is the reluctant creator of the original Thorns - they're a side-effect of experiments he's doing, trying to figure out if there's some way to make Cheshires immune to the destructive effects of pure water. Despite the original Thorns being errant, uncooperative experiments, he only invests minimal time in bothering with them - usually he leaves them alone, rightly assuming that his time is better invested in trying again.

That said, if Nightshade are going to evolve into too much of a thorn in his side, he might begin being far more aggressive toward them.