Disclaimer: I do not own Buffy the Vampire Slayer. No profit made, no infringement intended.
You kept a part of her inside you, from when you were forged from the same prophecy. In her first death was your calling, and in your almost death was her almost freedom.
She'd known she'd failed as you smiled and let go into the tumbling black. She knew you still had that part, from when harlot lips met soft pink and your souls echoed, a warped mirror in two jagged parts.
She'd tried so hard to get that piece back, knowing she'd have to break you. She'd smashed you like a piggybank, eagerly searching everything that fell from you. She couldn't have known that you'd already taken that piece and slowly grew yourself around it, until it was a part of you.
She couldn't have know that you loved her, tragically and angrily. She couldn't have know unless she'd taken a moment to ever look into your eyes. Then she'd have known instantly.