Severus had been, truthfully, in a wonderful mood, all things considering, but he was a Slytherin, he was a Death Eater, a murderer, and capable of great acts of nastiness when he felt angry, upset, or defensive.
Having his entire life decided for him and having it made into some terrible tragedy hardly made him feel any better about life. It wasn't him that lost Lily, it was some great twat author who'd decided he'd suffer. He hated that. It made him seethe.
"I must've been a pathetic fool," Severus said from the kitchen, dropping the tray into the sink loudly, "And I taught? I loathe children... I think you should go back to your husband now."