When you nearly escape death by cremation, you activate your quirk as a reflex. Except, in the dire situation, you weren't as focussed as you normally are when using your transformation type quirk. The patchwork criminal that had frightened you, is now a small black cat. Since this is technically at least half your fault... you should take care of him until he turns back and can fend for himself again. Right?.. A DabixReader fic, in which you've turned Dabi into a cat.