Trill

One of Ecclesiastes' two familiars that they say they created out of their own magical power (and the cats back this up, so can you really argue?).  They can summon Trill with a snap of their fingers, and she usually helps with anything Ecclesiastes can't do alone, such as reconnaissance, assisting with a ritual, or you know, just doing the chores around the house.  She also has some mild arcane abilities of the "quadruped telekinesis magic so she can hold things like a biped with opposable thumbs" variety, and all three can communicate with each other mentally.  It's unknown where the cats go when they aren't summoned, and they don't comment on this beyond saying they're "around."  

Trill is the light blue, better behaved, and calmer one of the two, but still doesn't hesitate with a sarcastic jab when the opportunity arises.  Of course, her and her brother's biggest target to dunk on is Ecclesiastes themself, which is probably something you could psychoanalyze for hours if you see them as a hivemind.

According to Ecclesiastes, they're cats because...they like cats.  Interesting!!

A roleplay character, and thus can work in a variety of settings, even without Ecclesiastes.  Familar hijinks are preferred, but not required.  She could just be a magical cat!