The fight against the Hydra could have gone very differently. The Hydra had no reason to spare any of them. They had all attacked her as soon as she broke out of her seal and wanted to return to the world, after all. If anything, she would have been justified if she returned the killing intent.
She had more than enough strength to realize that killing intent.
However, whether it was intentional or not, Zach had defused the situation multiple times. Instead of the fight devolving into a blood fest to celebrate the Hydra's return, it turned into a conversation. It was interrupted by violence and unlucky choices of words, but Zach had essentially disarmed the Hydra by talking with her.
If he hadn't done that, the others would not have thought to converse with the Hydra or tried to figure out her intentions. They would have fought to the death, believing in the tales told by their predecessors and the prophecies as read from the stars.
