It's the orange horns that catch his eye. Reynir sees that flash of color, that he was sure wasn't there before. He turns automatically to look, wary of any danger...

And he sees that Ami is gone, replaced by someone else entirely. Except he had been holding her wrist, hadn't felt any change or any moment when the contact shifted at all. But the girl standing there is... wrong. Her skin is wrong and she has horns and her eyes are just - blank.

Reynir lets go of her at once, stumbling back, blindly, anywhere, just to get away from her. His eyes are wide with sudden terror, mouth open in shock. His voice is high and cracked with fear as he says:

"Wh-who are you?!"

Because this is definitely not Ami. Ami is gone, and this - person has replaced her, vanished her away somewhere.