The other horse with her is also a mustang, though one that is a little further along with her training. Cascade was in the holding pens for the BLM for two full years, so she's pretty used to being in close quarters with other horses. She was actually really gentle, definitely dominant, but never in a mean way with the other horse.
Even now, it's more that they're both a little pushier than they have been. The trainer says several of the other mares are in heat, so everyone in the group is a little on edge. She's not concerned, and still hasn't shown any sign of honest aggression since she's been at the trainer's. I don't blame her for being a little irritable, it's been really hot and humid the last few days.
I can't wait to see her again.