She was always detached to a certain point, able to take a step back and turn her back if necessary. She tried her best, she committed. But there had always been the option to just leave in case a deal breaker happened.
She'd been this way with both Matt and Tyler.
She'd always thought that this applied to Klaus, too.
She saw him rip out the girl's throat after he'd drained her into unconsciousness, found herself immobile watching the evident glint of enjoyment in his eyes, mesmerized by the echo that the sound of the body falling to the ground created in her head.
She knew this was a deal breaker.
And she also knew she could not turn her back on him.
She knew, instinctively, it had become a core part of who she'd become, that she could not leave him.
She needed, needed him, like she'd needed air as a human.
Eyes widened in terror, she felt the tingling all over her skin, the dread spreading in her chest.
This meant that she was trapped. That no matter what he did, no matter how this turned out in the long run, she'd be at his mercy, unable to leave. And the monster was still very much evident in him, right before her on clear display.
So when he turned his head and saw her and realization spread on his face she knew that this would be the last thing she'd ever see on it.
Because this meant that she had no choice left but to do exactly what she found herself unable to, to turn her back and leave, forever.
So she did.