What makes someone intimidating
In this case someone may need to just get more experience with the world and see that tons of otherwise good, nice people often skirt the rules in one way or another.
They find them to be too macho, aggressive, cutting in their humor, or unpredictable.
They may feel that way because they got picked on as a kid, or because they never really felt like they fit the male stereotype.
Here are the big ones: When someone is intimidated by really outgoing people it's that they're worried about having to talk to them and feeling really overwhelmed and like they won't be able to keep up or know what to say.
There's not much to getting past this one except more practice with social and conversation skills so you feel more comfortable in their presence.
This is sometimes more of a problem for people when they're still in high school, when all kinds of students are mixed together and they may run into characters like this.