If your Inquisitor is serious and broody -- it mightn't be the best fit. But if she doesn't take herself too seriously, is easygoing, if she has a heart and gives a damn about people, then by Andraste a Seramance is almost mandatory.
This doesn't address your problem at all but fwiw I think Cadash gets the cutest Seramance, so I think that's a perfectly valid choice as well (since you were considering it).
Again, I'm not big on age gaps, so I think a Seramance works best with a very young (teens to early twenties) Inquisitor, one who's more than a bit intimidated by everything and afraid of being turned into a symbol and losing themselves.