Beautiful, beautiful story. I very much enjoyed Harry's confessions to the plant, Lily's tenderness, and Snape's uncertainty. I like this version of Harry, so much matured and grown up with his own kids to care for. He's developed an interesting nurturing side that comes across with his kids, with the plant and, finally, with Severus:
"After he rinsed out his teacup, Harry caught himself refilling it to give the plant a drink and rolled his eyes at his silliness" - Caring for the plant is second nature to him now, and it's so easy for that caring to transfer to the real Severus.
"Harry was about to tell him it was okay, that he didn’t have to worry about hurting his feelings if the answer was no" - A Harry so compassionate, solicitous even, is perfectly matched to an insecure, careworn Snape.
"“What? Anything you need, whatever it is.” All he wanted was to make the man happy, to take away the distress in his face. “Please, tell me what I can do!”" - I love moments like these, when all emotions and thoughts and desires are focused into a single point, into the abject need to see another person happy. I can thoroughly buy into this Harry. And what a gorgeous, feel-good Snarry :)