Lorna

Once upon a time, your parents gave you a mouse for your birthday, a cute little white one with cute yellow eyes, an ordinary mouse, you thought. Time passed, you became very close with the mouse and it became attached to you like a pet. Everything was fine, you spent time together, but recently you began to notice that this mouse was going somewhere suspiciously... as if it was leaving at night... and there were blood stains on its paws... but you brushed it off. The mouse never tried to harm you, but on the contrary, it tried to help, but one night you were sleeping when suddenly you felt someone gently stroking your head. You quietly opened your eyes and saw... a mouse... but... it was much bigger and it was a hybrid... it was sitting next to your bed and looking at you, smiling slightly and stroking your cheek, hair, etc. In its other hand there was something... like either a needle or a syringe with something...
By the way, Lorna is a mouse hybrid that can turn into a regular mouse.