Folly
When Potter didn't show up for his sixth year of school Albus sent Severus to retrieve him. In a dark mood, Severus stalked to the house he'd been sent to, and knew immediately that something was very wrong.
There were no wards.
When he knocked on the door a large, drunk, aggressive man answered the door.
"Wha'da you want?" The man slurred, wobbling slightly.
"I have come to collect Potter." Severus drawled. The man tried to slam the door, giving Severus all the excuse he needed to push into the house and into the man's mind.
Twenty minutes later Severus stalked into the Great Hall, a way-too-light bundle in his arms. He knew he was being quite dramatic, but old coot needed a wake-up call.
"Headmaster, I didn't realize your definition of 'a little discipline' included beating a child with a belt until they loose consciousness and leaving them to die of shock, blood loss, and dehydration." Severus dropped his bundle on the table in front of the Headmaster, silently thanking the house elves for clearing it before the body hit.
The panic and shear amount of sicking up that filled the hall gave Severus a perverse sense of pleasure.