Cosima's expression fades, a bit, into wary neutrality. "Probably best not to leave her unsupervised for very long, then," she says, fairly evenly. She's doing her best to trust Sarah on this, but it's hard for her to imagine what they must have gone through to get to this point. Helena is still Beth's unfinished business as much as anything else, for Cosima, and it's jarring for Sarah to sound even gruffly concerned about her.

On the other hand, Sarah's instinct for self-preservation isn't one Cosima generally questions. She's willing to try to catch up.