She looks at him, looking at her.

The look they share is a treacherous one, rough and challenging.
She's daring him to go further with his unrespectful teasing with her stare, hoping that her narrowed eyes could be intimidating enough to prevent him from adding other creative insults to the ones already muttered -muttered, yes, but loud enough to be heard all the way across the silent class, from the last desk where he sits to the chalkboard where she writes.
They're relationship is a treacherous one, rough and challenging.

And he looks at her, looking at him