Charming on the outside, devious within, prince Hermes was nothing what his parents expected. Turns out his trickster side makes no exceptions for family and was a very troublesome youth. His father was thrilled at first, announcing to the kingdom, that his son is the heir to chaos, but was soon growing concerned to his son not showing remorse after his pranks. After much thought, the prince was sent to Ponyville, so that Twilight could help him and he was not happy about that.
With everyone being so nice to him, he resorted to locking himself into his room all day until, as Discord's last attempt, Fluttershy went to talk to him. He explained to her, that he pulls pranks on others because he hates it, when they're being nice to him, but don't actually mean it. He has an unusual ability, to sense other's true feelings, even when they're lying. He knows what his father did in the past and that stigma still resides on him, especially on his appearance. So when he came to Ponyville, he was confused, when ponies would talk to him and their aura matched their words. Scared of being hurt, he locked himself into his room, where it was safe.
After that and much of the staff changing in the castle, prince Hermes was brought back home and is now training, to aid his mother in ruling, by pointing out frauds and liars during meetings.