[Steph seems to consider that for a moment before nodding in earnest understanding; she might not know his full powerset, but considering all the weird magic users she's met and knows of, it's probably better if Billy stays sensible.]

You know how they tell you that when you add a new cat to the house you should like, keep it separate from the other cats and let them sniff each other through the door first so they don't get overwhelmed and immediately hate each other? Tim's kind of like that with new people. He'll warm up eventually, it just takes a while.

[She isn't sure exactly what Billy knows about Tim and Loki, so she's not outright going to say anything about their relationship; she can just comment on the basics of Tim's personality.]