Late night drinking with your sister, and you shift from the catching up and inside jokes to serious talk as you both get tipsy. You get a bit closer and ask if she's seeing anyone lately, she says no, nobody ever loves her how she wants. You feel your heart break, and you hold her close, you say "they dont deserve someone as lovely as you, none of them", and feel her sob a bit about how lonely she is. You kiss her on her forehead and pat her head sympathetically, saying you know. She's so warm, you hold her maybe a moment too long, but when you finally separate, you pause and look into eachothers eyes. Her breathing is heavy, her eyes are sparkling, and before you can think she kisses you on the lips. You're stunned, wondering if that really just happened, when she says "Sorry, I've...had too much to drink," and your heart droops, but you hear yourself say "It's okay, I...I want it too," against all your better judgment. Both of you freeze. She wants to say "but we can't...", but she doesn't. Suddenly she's on you, making out with you, and both of you know the line has been crossed, the taboo has been broken. It can't be fixed again, and neither of you think it should be.