Rape is a serious and emotionally traumatic experience, when it happens to anyone regardless of sex. The majority of people who are raped, know the rapist prior to being raped. I recently read a story that dealt with how a girl who was raped and the people around her dealt with it (boyfriend, classmates, and parents). In this particular story the girl's parents decided to move away and tried to start a new life in a new place but it haunted her. She had nightmares, washed herself raw trying to get the feeling of uncleanliness off of her. Was scared to go near males. Was scared that people would find out. Even went to the point where she attempted to commit suicide over it. The story ended positively with her getting on with her life but it is implied that it would haunt her for her entire life.
Rape in fiction though is not always considered bad. In fiction there is occasionally the idea that people enjoy being raped and will fall in love with their rapist. Another way it displayed is that it is not rape but instead the guy was overwhelmed by her beauty or something and had sex with her and the girl was ok with it. This is seen in James Bond movies where he forced himself on the girls and they instantly fell in love with him.
Then in fiction and sadly in real life females raping males is not always considered rape. Often it's not even considered possible. Too many people don't seem to realize that erections are involuntary not voluntary. That even though men are generally stronger than women they can be date raped (drugged), tied down, or coerced into unwanted sex (female boss threatening to fire male employee or something). Inserting unwanted things into a male orifice does count as rape. There is also massive social, political, and legal double standards involved in females raping males. Guys supposedly want sex always. Males have a much tougher time finding support from rape crisis centers and the like. More info here: http://www.vaonline.org/vls6.html (there are quite a few other sites as well)
Of course there is also males raping males and females raping females. Prison movies/shows use this fairly often. It generally like most rape is about power more than sex.
In Ranma fan fiction Ranma being raped shows up a few times. While it never actually happens the topic does show up in the Ranma manga a few times (usually played for laughs). It is shown to be a valid fear for both Akane and Ranma. Here are some examples from the manga: Akane during the time Ranma tried hugging her because of a magic compulsion was scared Ranma was going to rape her. Akane accused Ranma of trying to rape Miss Hinako. Ranma had nightmares of Kuno taking advantage of her/him and having Kuno's children. Akane feared Kuno would take advantage of a drugged Ranma-chan. Densuke took Ranma-chan after drugging her to a love hotel with the intention of having his way with Ranma. Kodachi temporarily paralyzed Ranma and was going to have her way with him. Shampoo had restrained Ranma and told him to have sex with her or she was going to kill Akane. Etc.
Some of the Ranma fan fics that deal with rape are actually pretty well written. Some deal with how even a super powered individual can still be raped (usually magic or drugs though at least one was Nabiki using blackmail of some type -don't remember the details). Others dealt with how there aren't support groups for males (have Ranma go as a female but reveal that he is actually male). Some don't really deal with rape itself but instead make a comparison about how Ranma's curse (other character curses could be compared but haven't seen it) is in some ways like being raped; In that Ranma has no control of his change, feels himself to be worthless because of it (or less of a person/man), can instill the same feelings as rape does anger, degradation, fear (for Ranma fear of being splashed/changing at inopportune time), confusion, shame and/or embarrassment and is constantly reminded about it. Ranma is told that it's not so bad and to accept it. There are probably fics somewhere that deal with Ranma being raped as a male (probably by Shampoo or Kodachi) but I don't recall any except one where Nabiki does it. Of course most are just bad fics. I've seen one in which Ranma raped Akane and everything turned out fine. I've seen one where Ryoga raped Ranma and Ranma started to like it, etc. Don't ask for links because I don't have them since I dislike fics involving rape even if they are well written and are otherwise good fics (will usually stop reading the fic unless particularly good).