Sofia the First. She is one of Amber and Clio's best friends and one of the most popular princesses at Royal Prep. She is voiced by Coco Grayson.
In terms of personality, Hildegard is very much like her friend Amber, in that she tends to be snobbish, self-centered and having a tendency to act aloof to those she finds beneath her. However, in the episode "Baileywick's Day Off", Hildegard is seen showing a greater tolerance for Ruby and Jade, likely due to meeting them in earlier episodes.
Hildegard is also very proud and confident in herself. Her stoic personality is what separates her from the other princesses. Usually, Hildegard will be seen wearing her haughty smile and carrying herself in a manner that tells others she's "a cut above the rest." In fact, as Zandar finds out in trying to impress her, she is only truly pleased when in the spotlight.
In "The Princess Test", however, that image withers away. When Hildegard feels the pressure of an important test, she tries to hide herself away, not wanting her friends, especially Amber, to see her in doubt. However, Amber, donning the maternal role Sofia played to support her, offers some words of encouragement and Hildegard regains her confidence, thus passing the test.
Hildegard, though mostly like Amber in nature, does have some contrasts. Unlike the flamboyant Amber, Hildegard has a taste for simpler styles. She liked Sofia's small garden tea party, saying it reminded her of countryside picnics. She is also willing to try new things if only to find something to impress her.
In "Scrambled Pets", she is revealed to be a snitch. She whispers to Clio that Amber, James, Sofia and Vivian will get in trouble for bringing their pets to school. This is looked upon further when she tells them that she let Freedo out so she can be the teacher's pet and make the other kids look bad.
In the episode "The Princess Stays in the Picture", Hildegard finds herself confessing to Sofia that she acts the way she does because she thought that, after embarrassing herself on the first day of school, the only way to get other people to like her was if she acted like a perfect princess with the answer to everything. Sofia told her that it was better to be honest and humble so people can see the real Hildegard. In the end, Amber noticed that Hildegard changed and that Hildegard and Sofia are now closer as friends.
In "Sidekick Clio", her friendship with Clio is explored more. Its revealed that she won't let Clio do anything she likes unless she likes it and they do it together. It took some choice words from Amber and watching Clio on stage, to realize that she had been acting very selfish. Reconciling with Clio, she agreed they could do what Clio wanted, from now on as well because they didn't have to do everything together.