Sofia the First, She is voiced by Harley Graham. In "Sidekick Clio", her singing voice is provided by Jenna Lea Rosen, who also provided the singing voice of Princess Hildegard in "The Princess Stays in the Picture". She is the Princess of Corinthia and close friends with Princess Amber, Princess Hildegard and Princess Sofia.
Unlike her friends, Clio is more open to things that are not considered for princesses. In "The Big Sleepover", she is the first to admit how nice and fun Jade and Ruby were and even defending them at one point when they accidentally knocked over the chocolate milk fountain and spilled a drop of it on Amber's nightgown while they were drenched and laughing at their silliness while they're playing 'Pin The Tail On The Unicorn.' Even so, she tends to follow Amber and Hildegard's lead, going along with whatever their opinion is.
Throughout the series Clio has always done what Hildegard wanted because she said that's what best friends do. In "Sidekick Clio" it is shown that Clio didn't want to lose her friendship with Hildegard by doing things she liked. With some help from Sofia and Amber, Clio finally stood her ground and told Hildagard that she was going to audition for the school play, because it was what she wanted to do. After winning the lead role and putting on a spectacular performance, she and Hildegard reconciled, with the latter realizing friendship works both ways. This marks the first time Clio wasn't submissive to others and may affect her in the future to be her own person.