Lure
One memorable Christmas gathering at Grimmauld Place, Hermione Granger went to Severus Snape to offer him something too good to refuse. By that time, she had long ago broken free from the chains that bound her to the Weasley family, and had found her own style and corner in the world instead. Every argument he had she proved invalid with self-confidence in her voice and with an ease that betrayed how much thought she had given the matter.
So they went upstairs, and not even one questioning glance followed them because the party was loud and chaotic. And on this very night, she showed him heaven and hell, and when he left in the morning, it was a sad leave, because he was sure that it had meant to be a one-off thing, the outcome of a suggestion spoken out loud by a drunk woman, a night without a chance for repetition.
Catch
But Hermione Granger came back. She came across him in the ministry, casually touched him, and smiled one of her mysterious little smiles. Once having experienced the sensation of being her sole focus of attention, he couldn't forget the feeling of being wanted, being loved. He sat at home, sensing the loneliness creeping in the corners of his house, and wished she would give herself to him again, if only for the illusion of love.
She visited his apothecary to buy potion supplies, and their fingers brushed. He stared after her when she left, and went red when she looked back and caught him at it.
A month later, defeated by her evil seduction, at one of the social meetings the Order of the Phoenix did these days, he made his advance. For a second time, they left the gathering together, and that night, Severus Snape lost his heart.
Keep
Severus Snape became aware of what a splendid woman she had become. Hermione Granger was polite. She was powerful. She didn't wear her heart on her sleeve anymore; on the contrary, she had become quite cunning. She played the game of power and was so skilled at it, it put Percy Weasley to shame, but at the same time, she knew how to satisfy her allies. She didn't have to take anything by force, they handed it to her on a silver plate. She had proven herself to the pureblood society, but her old friends regarded her still as a simple Gryffindor.
Oh, how they underestimated her. He was proud and in awe.
As a mudblood sidekick, she had started, and now she was one of the highest Unspeakables, and if she had a long-term plan – and he didn't doubt that she did, somehow, he suspected that he was even part of it – she could be running for Minister of Magic in a few years. He had watched her for long enough to see that she was fooling her peers, secretly making friends with influential people, but not making these connections too obvious.
She came over to his house more often, and he realized that he loved her and that he didn't want her to fly away once she saw how old and damaged he was.
Consequently, he bought a ring.
She accepted his marriage proposal with tears in her eyes, and he was relieved by them, as they proved her feelings for him to be true. It wasn't just a scheme to her.
Epilogue
And that was how Hermione Granger became Hermione Snape. Severus Snape supported her campaign, he did her paperwork and rubbed her feet after a long day in heels, and he couldn't be happier.
"Did you plan it all?" He asked, sitting in the living room with his witch on his lap, the loneliness having long left the house.
"Of course," she said. "Luring you with sex and catching you with love. And I kept you by giving you everything I am."
And he was perfectly fine with that.
