Have just watched all of Season One in one sleepless go. Some parts good, some parts very very bad, but mostly worth it so I can read your ficlets.

Demon!Ianto. Yes. This is now my canon.

He’s only half demon, Ianto assures them, in his ever-so-slightly-creepy tone of mild amusement. It’s impossible to tell if he’s joking or not.
He passes them each another cup of coffee, and promises not to send them to hell, unless it’s Owen, and then only if he’s very irritating.

This is scary-accurate. I can see him doing exactly that in exactly that way.