Isis stayed close to Osiris for now. When it came time to fight, things would change and while she wasn't the worlds best fighter, she wouldn't give up. Set had pissed her off one too many times in the centuries and killing Osiris and the others this time and been the last straw. She was done. If she had been allowed she'd have killed Set herself. But she knew Osiris didn't want that, and as much as she hated to admit it, she didn't want to kill her brother either. Ring his neck, of course but not so much kill him.
Staying quiet while Osiris spoke, while everyone decided where they were going, she waited until some went to deal with the occultists and then looked at her husband, "this ends, here," she said seriously. "We need this to be done, him to be either back annoying us, or in such a fashion he can't cause us harm anymore."