Fenris and Isabela seemed to have something going on in DA2 if neither of them was romanced by Hawke.
From the wiki:
Isabela: That night...I can't stop thinking about it.
Fenris: Well, then I'll see you later.
Isabela: That was direct.
Fenris: I thought I'd get straight to the point. Were you expecting flowers or something?
Isabela: Don't be absurd.
Fenris: Then I'll see you tonight.
And:
Isabela: So, when we get back to the city, do you... ?
Fenris: Not in front of everyone, if you please.
Isabela: And he blushes! So cute!
Of course, I failed to get Fenris in my one DAII playthrough, so I didn't get to see this in game. Still, since it's been done once, I hope it'll happen in Inquisition.