[quote=natsumehack]
Even then you must ask the question, why would a person RAPE another person? 
[/quote]
See my first point. There is probably something wrong mentally in the mind of somebody willing to do the deed already.

[quote=natsumehack]
What does person A get out of doing this action to Person B?
[/quote]
Could be any number of things. Maybe they want to feel in control, maybe they're a sex-addict, maybe they do it because they know it will scar person B deeply, maybe they feel entitled. It's like asking why someone performs any sort of heinous act against another person. There are a ton of possible reasons.