Thea considers the rusalka, who looks... mostly just like a nerd. There's a laptop hanging off the back of the chair. A tray that folds out in front to hold the computer, a tarot spread, or both. Basia's fingers are stained with lab residue, in amounts that suggest, to someone who's made a lot of handoffs bartering tech for potions in back-alley labs, that she's not very good at getting efficiency out of her brews despite being an Academic with an intuition for it.
No sign at all that she's dangerous. Or exceptional in any other way.
Which is a weird sign in itself. Tesera wouldn't awaken a third-rank witch and then take her as her personal favorite bedwarmer just because she was cute and blushed pretty when bossed around. She'd probably get off on it, but Tesera never does things for one simple reason like that. That's half the problem.
"Okay. I underestimated you. Still not sure why I should believe you."