I know why Bioware made it where you can't Romance Varric.
It's because in all his Dwarven Author swag all the other companions look so bitchless in comparison and no one would want to be with the other love interests if they made him romanceable
Realizing how compassionate Cole would be to a traumatized, returned-from-the-Fade, quite insane Hawke who doesn’t know what is and isn’t reality anymore… I genuinely think if Fade-crazed Hawke encountered Cole, he could get Hawke to come back to themself enough that they could finally recover.