Three years ago, when she was nine, Angela (who also goes by "Susie") convinced everyone that she should be the mayor of Little Lamplight. When the kids finally agreed, she immediately issued that her first act as mayor was to change the title to "Princess." This so irritated young MacCready that he punched her in the nose only five minutes later and told everyone he was in charge from now on. Ever since then, she has had a crush on MacCready. She's been known as Princess ever since.
Bully the Bully: Princess may be prissy, but she has a soft spot. If you have rescued Sammy from Paradise Falls, he will join Princess in guarding the back gate and relay to you information that you may confront Princess with, to "take her down a peg".
Bringing up the origin of her nickname will make her cry and run off, resulting in negative Karma.
Choosing the Charisma option of remarking that MacCready spends more time with Lucy will cause you to lose Karma (only 1 point), and she will no longer talk to you. You can get her to talk to you again by asking Sammy about her nickname, and then asking if she still holds her grudge.
"Hey, new kid. I don't know if anyone told you yet, but let me set the record straight. I'm Princess. When you're around me, I'm in charge. You shut up and do what I say, because I'm boss around here. That clear?"