Okay so basically this is a plot twist of my favorite girl, Corgi, that she wasn't actually a bimbo and under her facade of cutesy and dumb.. was actually a dangerous mob boss who shape shifted into her because she died in a terrible accident>:)
The reason why Corgi hates miere is because he saw who she truly was.
Corgi died in a terrible accident and was impersonated by a shape shifter mage that could after their appearance to search for benefits.
They saw her dead body, hid it and took Corgi's appearance, since corgi was in an accident, the mage had to hurt it's appearance so the ambulance could treat the injuries.
And no one suspected a thing.
Everyone was worried sick about her! How badly the accident was and how she was alive, such a miracle, right?
Corgi was always the one with the sharpest memory of everyone, always the reminder tool of everyone and suddenly.. she was the most forgetful of all of them. But everyone just thought it was due to the accident.
Everything wrong was due to the accident, right?
The mage had to pretend to be corgi, following her habits and routines by everyone's words, they hated how.. naive corgi was, no wonder she died.
But the problem was.. Miere, the best friend of corgi who started noticing something was deeply wrong with his corgi, her soul was.. different, it didn't shine as it used to and it made her tense up even when corgi didn't mean being checked.
Everyone told miere that it was probably his imagination when.. he knew something was wrong, that was not HIS Corgi, that was not the girl he loved and cared about.
And one day he came unexpected, wanting to know more about this.. corgi that was supposed to be his best friend, he knocked but got no answer so.. he remembered, corgi trusted him with an extra key to her apartment so he entered and what he saw.. deeply traumatized him. That.. that thing.. wasn't corgi, that mage's transformation was.. disgusting.
He saw how Corgi's body shifted horribly to the mage's true body and.. it made him want to throw up, of course the mage noticed but Miere ran away, completely forgetting he could teleport away.
Since then, "Corgi" hated Miere's guts and he could just.. pull away, too afraid of saying something wrong and that creature would haunt him down.
That "Corgi's" have been getting more believable by the others, adapting even better each day so no one suspects a thing.. they would never know that the one inside Corgi's skin was the deadliest mob boss known in Ebott, always working from the shadows and attacking when on low guard, the mage had a reputation to uphold even if that meant pretending to be someone else, someone else that was dead in front of everyone's eyes and no one knew a thing.