In a rare breach of lab protocols - though there wasn't anything actively brewing at the moment, and it was nothing a simple Scourgify wouldn't fix - Severus hitched himself up to sit beside Al on the workbench.
All the better to be able to drape one arm over Al's shoulders in a sideways hug, leaning in so they could rest, each supported by the other's body.
"I really hadn't been expecting you to want to hug me," Severus confided. "I'm the last person anyone thinks of when the concept of 'huggability' comes to mind.
But then you started to, and you stopped. As though you thought you wouldn't be wanted. And I didn't want you to think that.