Silently, Cosima is amused by his flapping, as well as somewhat smugly vindicated. Any and all self-satisfaction gives way to sheer, blunt curiosity when he launches into his explanation. Briefly, she wishes she had a notebook with her, she'd love to take notes on this; but with no such thing to hand, she'll simply have to do her best to take it all in.

She nods along with him, eyes going wide and impressed when he describes the process of regeneration. There are creatures on Earth with what's called biological immortality, usually very simple animals that can regenerate cells, or that one jellyfish with the ability to revert to sexual immaturity before it dies and repeat the cycle over and over. But for something like it to occur in a complex, sentient being is astonishing.

When he pauses to ask if she's following, there's the beginnings of an avid smile twitching around her lips. Possibly that's inconsiderate? Given that the guy's telling her the doubtlessly traumatic tale of how he came into being, but that's just frickin' cool.

'Yeah,' she assures him. 'Like, um, transdifferentiation? Though obviously on a massive, massive scale. Was that a natural development in the species, or was it engineered?'