We know that Rudeus was reincarnated, but if you think about it from an outsider's perspective Roxy hitting on Rudeus is a 50 year old hitting on a 16-year old. She ain't a Demon, she's a cougar!
I wonder if a hydra makes its decisions through voting and majority rule. It has so many heads that simply debating every time until consensus would take a good portion of its whole life.
If you want to play fantasy biologist I would consider these possibilities: there's one main head and several backups if the main head is killed one of the backups takes over, but otherwise each head isn't a head in the traditional sense and act more like appendages like arms and legs.
The "brain" exists closer to where the necks begin and the heads do not have a brain
Each head acts like an LAN connection they all have individual wills but have to communicate that will to a centralized brain which can overrule an individual head. This is most like what you're thinking, but would happen so fast that it wouldn't really be conscious of making these choices
Even if you know what is about to come, you cannot help but shed tears.
I got Hammerfall's "Restless Soul" queued up
did the author ever make an "IF" of what is coming?
Not that I am aware, but probably not and to explain why would go into spoilers