No sexual tension necessary. Just two post-apocalyptic badasses at the top of their game who, after a rocky start, begin to share the same goals. Oh, and they just happen to be a man and woman. Interesting that you can successfully portray a relationship between opposite genders as being one of mutual respect and not have it devolve into any number of overused tropes that tend to characterize the relationships of those who do not share the same set of genitalia.