Severus had always hated his name. It was so old-fashioned, and long, and decidedly not normal. He hadn't grown up with other children, so it wasn't as if he was taunted (at least to begin with). It just didn't seem right, it didn't feel like it described him, the boy who was kind and good and had all the beauty crushed out of him before he'd even boarded the Hogwarts train. The boy who was lonely, so terribly lonely that it showed in his face and his manner and his words, which only made him strange, and even lonelier.
He thought Lily's name described her perfectly. She was beautiful, and joyful, and pure and quiet and loud and brave and bold and vulnerable. She was perfect, like the perfect flower for which she was named.
But for a long time, it didn't matter. His father called him "boy," and his mother prefixed that with "stupid." And he had no friends as a child.
And then along came Lily, and he would have noticed her even if she hadn't been a witch (because she was perfect).
When he realised what she was, and knew that she didn't know yet, because he was always clever and noticed these things, he was elated, because he could finally talk to her, and terrified, because she might reject him. For the first time in his life he felt the need for someone, anyone, to adore, to love with his whole being, because if you are as lonely as he was, being loved doesn't matter so much. What matters is being close enough to someone to love them completely and unconditionally.
So he did. He loved her, loved her when she was his only friend, loved her when he fell in with the wrong crowd, loved her when he realised that he wanted her so badly he couldn't breathe, couldn't think in her presence. He loved her when he watched her fall for the right guy, the man she deserved, the strong, handsome, arrogant one who would love her perhaps nearly as much as he did.
He loved her when it was too late (because she was dead).
(Because it was his fault.)
And it wasn't because she was perfect. It was because, even though she'd laughed the first time he'd told her his name, whenever she said it, it described who he was.
When she said his name.