As her name implies, Sweetie Belle is a true innocent among the Cutie Mark Crusaders, gentle, meek and soft spoken, with a constant desire to please. Though she has got angry and upset on occasions, for the most part she maintains a quiet, calm demeanor that adds a lot to the group dynamics. While normally following along with whatever Apple Bloom and Scootaloo are doing she will confidently lecture them when they are getting too hot blooded, and voice her concerns when she thinks what they're doing is a little too dangerous.She's unfortunately not too bright, and can be very slow on the uptake. A constant theme in her appearances is her ignorance about where they're going, and in Stare Master their new game caused a few moments of blank eyed confusion before she finally got the idea. When asked to think up something in a hurry she has obvious trouble, rounding off the CMC's goals with the nonsensical "No meal uncooked" in The Show Stoppers and repeated stating "I really like her mane" when confronted with Twilight Sparkles' doll in Lesson Zero. She also displays the most childlike speech patterns of the cast, and noticeably slurs her speech.
On the other hand she does have a incredible talent with all kinds of music, with a good ear for tone and a wonderful singing voice. Despite being normally quiet and soft spoken she can reach impressive volumes, and has demonstrated skill with both gospel, rock and more simple melodies. She also has a talent for song writing, with both tune and lyrics.
She has great respect for her sister, and dreams of being a fashion designer herself. Unfortunately, though the capes she designed in Stare Master were competent enough Sweetie proves both clumsy and poorly organized in The Show Stoppers. Making the parts of the costume the wrong shape, putting on too many legs, and forgetting to wash her paintbrush between colors her artistic skills prove rather limited, and are only salvaged by Apple Bloom's intervention. Likewise, her desire to help her sister are often rebuffed, and an attempt to aid her anyway managed to devastate Rarity's boutique.