[It's definitely Mystique. But with her penchant for disguise and especially for passing off as friends of the kids... it doesn't seem that there's any way he could tell for sure if she really is from her own past. She could be a Raven who isn't a monster yet.

Kurt realizes the most important part. She's a Raven - a Mystique - who is alive. It's not all over. She hasn't been shattered. She's right here in front of him, whole. Whoever she was, she's been befriending them all this time. Isn't that what he had secretly wished for from her?

He breathes carefully as he regards her.]

Whoever you are... In all this time, you haven't tried to hurt me... or her. Maybe you're not who I know you as. Either way... Things are different now. Maybe - maybe for the better!