We first see PA when Bella, Angela, and Jessica go shopping for dresses. There Bella is almost raped, but Edikins saves her. The second time she's in it is when she is seeing a movie with Jessica and goes over to a few guys to see if they're the same dudes who tried to rape her. Jessica, being the
rational jealous person she is, freaks out.
According to Meyer, Port Angeles is where all the rapists and criminals are. Meyer seems to have something against cities. Everytime Bella goes to a city something bad happens to her. Rapists in Port Angeles and murderers (sparklepire army) in Seattle. Anti's wonder why Twilight characters ever visit cities, seeing as they seem to house every criminal in the state.
This is a poorly constructed plot device, but hell, so is everything else in this shitfest.