Snape sighed, bowing his head, shoving his hands through his hair, kneading his skull as if trying to massage his brain into working. It was at one and the same time so perfectly self-evident and so utterly impossible to explain.
He looked up, met Al's gaze levelly. "I want to live with you. I want to protect you. I don't want to have to make an appointment to be with you, or explain myself to your friends. I want to sleep beside you, when we've tired each other out, and share the same coffeepot in the morning.
I'm hardly an expert on the topic," he concluded with rueful honesty, "but that sounds like marriage to me."