Perhaps the nostalgia caused him to get the blinding pain in his head and drop the Infusion of Wormwood. Or, more accurately, it might have been the vision of a young boy being knocked around by a giant brute of a man. Severus could have dismissed it, claiming it to be brought on by fatigue, but those green eyes and the lightning scar on his head brought forth a tug in his heart. They laid a claim to the promise he made years ago, one he had no memory of making.