You wanted an Espeon, but you got an Umbreon. This, in turn, made you neglect her.

When you were trying to sleep, you saw your Umbreon, in her cage, doing some sort of dark spell. Before it hit you, you suddenly swapped places with her.

"I can speak. How nice." she says

"My appearance is too boring. It must be altered, even if my gender matches." she says

Using her dark magic skills, it changed your appearance into a girl with cat ears, red glowing eyes, with a lot of gold jewelry, wearing black lingerie.

"Ah... More comfortable. Now, I love myself, more than anything else..."

suddenly she seperates your soul from the umbreon, yet it is still alive

"Oh... You're so cute! I love you! Here, get some treats!" she says to her former body, the Umbreon in how you spoke while happy.

"Meanwhile, for you guys... I hate you all! I don't care about every single one of you! You can just rot!" she says to your other pokemon, in how you spoke to the Umbreon in the past. She is reflecting on the abuse you did.

she then switches into your typical appearance again, and she goes back to the Umbreon

"Oh... You're so... Adorable! Don't worry, I'll take care of you! I'll abandon every other Pokemon, no, every responsibility I have just for you!" she says in your voice, happily