Ash has hypnotic powers, that may or may not differ in strength. Canon gives no details, but apparently, they're strong enough for him to let
a pile of people kill each other.
...or he killed them. Canon's fuzzy about that to. Ash is not perceptive with detecting someone else powerful/someone's powers, and he might just try to use his hypnosis on you, and they can prove ineffective. He
tried it out on the dragon Alecto in canon, and nothing happened. For the most part at least. Then again, Alecto's always been attracted to Ash, so that's a bad example.
ANYHOW, he does have powers, and this is where I ask you;
1. Can he use those powers on your character?
2. Would he even be ABLE to?
3. Would your character retaliate, how and with what?
Because if he finds it needed, he will try. Usually, this contains him just ... talking to you, adding in a
suggestion out of bounds. It won't neccessarily mean death, but. He can basically tell you to do anything, even the dirty work of murder if he wants, be it within his powers to persuade you.
He's certainly not overpowered, but those weak of mind should be careful to step on his toes~
That aside, everyone has blanket permission to take revenge if they're that inclined. Ash pulls trouble to himself, and he deserves the abuse.