[It does start out reasonable. He's already thinking on how picking up her groceries is a good idea especially if she was working late, good on her to think of something to mundane and easy just to fool the cops. And then...]

Your pet goldfish?

[There's only a hint of incredulity in his voice, part amusement and part surprise.]

Yoimiya, I think your goldfish probably doesn't need checking on, unless you're the sort of person who forgets to feed their fish.

[Of course, he has to tease her a little, his eyes peering at her with a half smile on his face.]

Why don't we just stick with the groceries, haha.