Orion always knew just how vulnerable his youngest was, and he'd give anything to keep Regulus safe while also allowing the boy to live the bright life he deserved. And then the attack at Hogsmede happened.
When Death Eaters attack Hogsmede, Regulus is stuck in between, which results in a loss for him.
Orion feels left out of his children's bonding time and asks his wife for help - even though Walburga is not the emotional type. AU! Good Black Family. No Voldemort.
When Tom overhears a snippet of conversation between Hermione and Abraxas, his overactive imagination makes a mountain out of a molehill.