There were so many things in the kiss that Terrence didn't fully understand, but he returned it, trying to process what it meant. Not because he was worried for them, but what she was feeling and thinking right now was a warning, of sorts. To steel himself against whatever he was going to find out next.
He looked at her for a moment when she broke it, wondering if he would be looking at her the same way even just a minute from now - less than a minute. Then he reached for his wand and cast the spell.
First, he found much of the same things he'd felt in the kiss. Things that he couldn't put a name to, either. He registered them, but moved deeper, not sure what he was looking for, not letting himself feel guilty for invading her mind, because she'd offered, she could protect herself if she needed to. There was nothing he was trying to see except for the one, terrible secret that she couldn't say aloud.