Your writing is stunningly beautiful. I love how this is romantic and realistic at the same time. The description of the shop, of the ingredients and plants, is perfectly sensual, and it becomes so clear why this is Severus's favourite shop. He's like a kid in a sweet shop, and taking the utmost pleasure is only consequential.
I love your Harry, the way he's comfortable with trusting in Severus. I love him chirruping and wearing boxers with little cauldrons on them. Most of all I love your Severus, brewing warming potions and sending chocolate bars. An exquisite story, one that I'll often return to.