To really understand where the fourth goddess comes in, you have to take her appearance on Earth in context. It was a normal day in the life of Keiichi (and don't all of his bizarre adventures start out that way?). Keiichi innocently picked up the phone to call Megumi, buuut just happened to dial the wrong number and reached a goddess help office... AGAIN! Who was more surprised? Keiichi, who was in disbelief that he had called another goddess, or Peorth who found the mortal that had just summoned her was already living with three? Peorth found the situation perplexing, although she and Belldandy were thinking the same thing: If Keiichi's desires had truly been fulfilled by his first wish, then Peorth wouldn't have been summoned at all - i.e. Belldandy wasn't fulfilling his wish. (but I won't spoil the real reason).
Peorth has a rather... quirky personality; or about average when compared to the other goddesses. She's confident, somewhat self absorbed, and a little conceited. If you cut through all that and her crazy antics, she has a kind and gentle heart. Not long after arriving, Peorth decides her role is satisfy Keiichi's carnal desires. It's not clear if this is the kind of thing she normally does or if she thinks Keiichi deserves the extra service. Unlike any other mortal she's ever met, Keiichi is surprisingly resilient to her provocative behavior. As is usually the case with females that meet Keiichi, she sees his kindness and starts to like him. She confesses her love at one point, but it's hard to tell if it's Peorth being crazy as usual or if she is sincere. Keiichi does know one thing though: a first class goddess never lies...
Aside from her adoration of Keiichi, Peorth takes a liking to comic books and spends her spare time reading them. She likes to inject French words into her dialogs. Many of her attacks stem [excuse the pun] from roses, like rose storms or using them as darts. Even Peorth's angel is called Gorgeous Rose. Although her age isn't stated, she is cited as being older than Urd. If you really want to think of a strange twist, imagine how things would be if Keiichi called Peorth first instead of Belldandy.
In her own words...
- Oh come on! You're a guy, I'm a girl. This is the best part right?
- Are you asking to be next on the butt kicking list?
- You missed out. I really do have a reputation for the very BEST service.
- Belldandy, there's something very pure and special about you, you know. It's quite annoying.