Train Heartnet (black cat) x reader

You are an assassin, your nickname is Shadow cat....... Your mission? Find the famous Black Cat, become 'friends' then kill him (I DONT own Black Cat or anything else only the plot of the story, I didn't see many black cat stories so please tell me if its no good. This is also on my Quotev account so if you happen to have a quotev and seen it i am the same person who wrote it.)