Steven freezes, his eyes lingering on Strange in a moment of shock. She... what? This is the first he's heard of any of this, and the knowledge that she's had some ulterior motive this whole time, when he'd just assumed she wanted him back out of raw possessiveness... it's a little chilling. Did she have him on purpose? For something like this?

What does she want with him? What has she ever wanted from him?

Steven's sudden rush of anxiety is pretty clear on his face, as is the way that he doesn't seem to know what to do or say in response. All he manages to do is warily take a step back, getting the feeling that Strange might have a connection to her, if he's claiming to know what she wants.

After everything that's happened, it has him already looking like he's ready to bolt.