Brienne is a bitch, in a bad sense. Low damage, no armor, pyromancer upgrade is pointless, constant "fuck me" scenes in tavern, questionable "pergnant" scenes... This is not yours bro.
On the other hand, if you managed to take Brint to the tower in ice wasteland and defeat ghost smith he will become and ultimate killing machine. Stagger enemies on damage, heal himself om damaging staggered enemy, high melee stats, does not require constant sperm injections for proper functionality... Definitely yours bro, not the one you deserve, but the one you needed.