A phobia is an extreme dread or fear of something. When a person encounters the object of his or her fear, he could experience anxiety, shortness of breath, rapid breathing, an irregular heartbeat, sweating, nausea, dry mouth, etc. While this person's phobia may seem outrageous or unreasonable to you, I assure you it is not unreasonable to the person experiencing it.
Never make fun of anyone with a phobia, but you can bless (or curse) your characters with any number of these fears. Pick one or more of the following phobias and create one or more characters who are afflicted with one or more of these fears.
Dystychiphobia is the fear of accidents. People with this phobia have a fear of hurting themselves or someone else. They could also fear causing property damage.
I can somewhat understand the fear of hurting yourself. Not too long ago, I fell while running down the hill outside of my house. I sprained my ankle and scraped my leg up pretty bad. I wasn't able to run for a while after that. When I was finally able to get back out and run, I was a bit scared. The thought that I could fall and kiss the pavement again went through my mind almost continuously, but after I made it down the hill once without stumbling, my apprehension left. My fear was not exaggerated (at least I don't think it was), so it would not have been considered a phobia. But if I refused to ever run down that hill again because of my fall, then it could have easily turned into a phobia.
Rhabdophobia is the fear of being beaten by a rod or instrument of punishment, or the fear of being severely criticized. Rhabdophobia is also a fear of magic and the paranormal. Hmm. What would cause an individual to have such a fear? Being beaten isn't fun, and I'm sure that no one would like that. But to walk around afraid of it all the time?
Maybe one would be like that if one was beaten severely as a child, even when one hadn't done anything wrong. A fear of being severely criticized? Maybe instead of being beaten severely, everything this individual has done, no matter how good or bad, has been severely criticized. That would definitely deflate a person's ego and self -confidence. I really don't know why a person would fear magic and paranormal things. Maybe a scary dream could cause this? This person could fear that great harm or death will come to him through magical or paranormal means.
Scelerophobia is the fear of burglars, murderers, or rapists. Basically it is the fear of being harmed by a wicked person. If a person has been repeatedly robbed or raped, this would be an understandable fear. One cannot be murdered repeatedly; that can only happen once. So maybe if one has been almost murdered several times, this would cause that fear.
This fear could also arise if an individual has watched a friend or loved one experience trauma because of being robbed or raped, or because he/she witnessed the murder of someone close. Maybe a friend or loved one was murdered in an extremely brutal manner, and he was the one to find the body. That would definitely be a traumatic experience.
Not only can you bless (or curse) your character with one of the above phobias, but you could also write the entire storyline around a the phobia. Take dystychiphobia, or the fear of accidents, as an example. If you are writing a romance, dystychiphobia could be the reason that your two main characters meet and fall in love. If writing a mystery/thriller, a fear of accidents could save a life or keep a crime from being carried out.