The choice will be between Nagare and Impisi, Terciero is a free spirit with a piety of 1, that is an extremely hazardous combination in our job.
Impisi seems to be the more promising, good martial, excellent learning and a bomb maker trait, that could help a lot. We just have to take care of the social stuff and paperwork on our own while he cooks bombs in our laboratory like a good terrorist/freedom fighter. We would have to make sure we are in a good relation, but it won't be impossible.
As for Nagare, the problem is that all of her stats are lower than ours, except piety by one point. It could be interesting to have two women marrying, but I don't think I like yuri enough to take the girl option if it doesn't have enough pros. There won't be much problem in the relationship with both sharing a huge religious background, but without an option to regularly improve her martial until she becomes a good fighter, Nagare will be a hard sell.