He shouldn't like this. She's straddling his lap and her lips are crushed against his. Her fingers tangled in his hair and his gripping her waist. He should hate this. He should tell her to stop, that this is a mistake that it's wrong. But all he does. All he can think is about is how good it feels when her hand finds its way inside his pants, and how he wants to make her feel twice as good. He shouldn't like the noises that escape her mouth as his lips close around her rosy nipple, shouldn't like the feel of her rolling her hips against his. He shouldn't want to be in her tight, wet heat. But when he thrusts slowly into her, he never wants to be anywhere else. He's known her his whole life, knows about all her little quirks and weirdness. But still he wouldn't want to be with anyone else. And she still wants to be his, though he doesn't know why. He shouldn't absolutely love the way she cries his name and arches into him when she comes, shouldn't be the cause of all her pleasure and he shouldn't shudder and slant his lips against hers and he spills inside her. He shouldn't be feeling this, not about her. Not about his little sister. But it's time to face the facts, he is completely and utterly in love with her. And he wouldn't have it any other way.