@Demons-run72 for your Harrypotter/Sherlock book, how about Harry gets smothered in care and love, but with time he gets annoyed and bored, and goes out, just to get kidnapped by Moriarty?
And Moriarty wants to let sherlock watch his son die by Snakevenom, but the little one gets angry as he sees his father hurt and hopeless, so he awakens by accident his Parselmouth powers, and the snakes attack Moriarty instead, and free young Potter-Holmes,
And make it a cliffhanger that Dumbledore felt his power awaken