In every dragon age game. There's that one character. That acts like the player characters best friend. The Warden has Alistair. The friendship can become something more if you want it. Oghren is a candidate although, he's always drunk. So won't remember whatever conversation you had .
Hawke was Varric as his or her best friend and sidekick. Whenever Hawke I looking to stir up trouble. Varric Is always there.
So the question is who fills in that role in the Inquisition. I don't think Varric counts twice. Vivienne is the only non romance able companion. However unless your politics match hers. She's nothing but a condescending hussy.
For me I guess the answer is Sera or Dorian. If the Inquisitor is a woman then Dorian isn't interested in her romantically. So their friendship is tied to a potential relationship. Same scenario for a guy Inquisitor and Sera.
I am curious to hear any other suggestions.