Although Snape had requested for his old portrait to be hung in his old Potions classroom a few years after the War, he despised dealing with first year students. They always did something wrong and it got under Snape's watched for years as they carelessly mixed potions and blew up their cauldrons.
One day, a boy with messy dark hair spilled his cauldron filled with 'The Draught of Living Death' all over the floor. He looked down at the mess, got to his knees, and began to scoop it up with his hands rather than use magic. Professor Slughorn was absent that day, and had left Snape to monitor the class.
"You boy! Come here at once!" yelled Snape across the room from his portrait, pointing at the boy. From the looks of it the boy was a Slytherin, wearing black robes with dark green lining. Snape recognized something familiar about him, watching as the boy hung his head in shame and approached Snape's portrait. "You boy, what is your name?" asked Snape in a cold and emotionless tone of voice. He had no patience for ignorant boys.
"A-Albus Severus, sir...Albus Severus Potter," the boy responded, meeting Severus's eyes.
Snape's breath caught in his throat - no, not from hearing his own name, or the fact that he realized this must be Harry's son, but because when the boy raised his head he saw Lily's eyes gazing back at him. An emotional lump got caught up in Snape's throat and he had to look away.
"Clean the mess up, boy. And do not be so reckless in the future," Snape ordered, still looking into Lily's eyes, the eyes he had not seen for so long.
Albus nodded. "Is that all, sir?" He asked, sensing something was off.
"Your name. Who chose your name?"
The boy hesitated before he answered but then spoke with a confident voice and proud smile. "My Dad did. He said I'm named after two headmasters of Hogwarts and the Severus one was the bravest man he ever knew."
Snape looked at the boy, wondering if he was being mocked. But Albus's face remained somber, and his emerald eyes shone up at Severus. "Very well. You may return to your potions."
Albus nodded, waved slightly, and wondered off back to his cauldron. A redheaded girl began to whisper to him immediately, and the two huddled over her cauldron, working. Severus heard a cough behind him, and when he turned, discovered he was no longer alone in his portrait.
Dumbledore was standing next to him, blue eyes sparkling just as much now as they had in his life. "A student told me once, Severus, that the things we lose have a way of coming back to us in the end."