Bellatrix whirls instantaneously on her heel, wand raised. There's some familiarity to the voice that calls out to her now, though she's not sure exactly what it is - until she lays eyes on Narcissa, at least. She watches her for a long moment, searching, and her brows knit, though it's slight enough that it doesn't make much of a dent in her otherwise steadied expression.

She stalks forward, one, two steps, wand not dropping so much as a fraction of an inch, and when she's standing directly before the other woman she comes to a halt.

"Who are you, to address me so familiarly?"

A part of her, long buried beneath the rubble of Azkaban, probably knows - but these days it pays to be certain. Her voice is biting, far from the tone a more polite query would warrant, but the superiority of it is the same as ever.