I also don’t understand what the big deal is about being to select whether the characters would want to kiss or not. In many games doing different actions leads to a different ending. Isn’t it good as it adds replay value? If you guys only played the game once how can you say that choices don’t influence the story that much?

A) Madison could have easily known from the moment she met him that she wanted him or wanted to somehow be closer to him. She could have felt a very strong attraction to a number of his qualities — she’s a woman and he’s a man, after all — and this kiss is a natural response to those feelings.

B) Madison explained her nature as the healer, the guardian angel, etc, when telling Ethan a bit of her life story earlier in the game. Ethan’s vulnerable and dependent state in Heavy Rain is something this character may feed on to feel emotionally well. She needs to be needed, and this situation is exactly the opportunity that satisfies her addiction to that feeling.