Prior to the events of "The Red Throne," Cinnamon Bun was very dim-witted and clumsy, even when compared to most residents in the Candy Kingdom. However, after being "baked" in the same episode, he becomes more intelligent and articulate in his manner of speech. He is currently Flame Princess' champion and knight and resides with her in the Fire Kingdom.
Before his change, Cinnamon Bun is shown to be dim-witted and somewhat childish in his behavior. He has a short attention span and has difficulty concentrating on even simple tasks. He is often oblivious to situations around him regardless of their importance or severity. Cinnamon Bun often plainly speaks about what is on his mind, giving him the impression of an honest individual.
Cinnamon Bun has a nasally voice that, when combined with his looks, makes him seem like an elderly Candy person. He is also very "soft" and can be easily damaged by small falls or bumps.
Cinnamon Bun was also very clumsy. In "The Enchiridion!," he attempts to do a back flip, but only manages to stumble backwards and crash into a tall tower holding Princess Bubblegum. In "Too Young," he is fooling around on a swing inside the Candy Castle, but quickly falls and splatters on the ground.
Cinnamon Bun had a short temper and often raised his voice when frustrated or scared. This is seen in "Power Animal," he yells at Jake after being ignored in the middle of their conversation. He also does this in "Dream of Love" when he yells at the audience when they are slow to leave Princess Bubblegum's concert. In "Another Five More Short Graybles," Cinnamon Bun is seen yelling "too dark" and "too light" after his nightlight is taken away by Princess Bubblegum in an attempt to force him to overcome his fear of sleeping in the dark.
Despite his negative traits, Princess Bubblegum often seemed inclined to assign him simple, but important tasks. In "The Other Tarts," he is originally offered to be the bringer of the royal tarts to the Back-Rubbing Ceremony, but Princess Bubblegum could not trust him due to his erratic behavior, referring to him as "half-baked."
However, in "The Red Throne," Cinnamon Bun demonstrates that he is very courageous and diligent in helping Flame Princess recover her kingdom. After being hit by fire during a skirmish, Cinnamon Bun undergoes a significant personality change as he is able to express himself clearly and demonstrates a degree of wisdom. [Source: wikia]
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