LOL! THAT LOGO! I can image a PR firm creating that and being super proud, and then the intern who sees it for the first time asking, "Why does it say NTR?"
@Lioslin remember the brother has perfect defense. My guess is that while the owl can't harm him, they can't attack it either. It probably keeps killing/destroying all of the sister's undead minions and that's why she's tired (from using so much magic).