[Again, he nods. It's.... about what he'd expect. She'd kept it sealed and been the 'face' of the conjoined being they'd become, and so the thing is probably drunk on freedom and willing to do anything to keep it.

Again his expression flinches into something like a cringe.]

...So don't believe a word of it. Got it.

[A pause and--]

She... told me before. She'd isolate herself, leave, forget anything before she was a danger. So... I know she'd appreciate you doing this.

[It's paraphrased, sure-- and she'd really only been talking about losing control and hurting him. But he'll take this to mean that she'd understand and be thankful for Seimei's sealing and guarding.]

I won't fuck that up.