Cinnamon is one of Jon's two (formerly three) pet parrots, alongside Jacques (and formerly, Spaghetti. Like Jacques, Cinnamon is also a green-cheeked conure, specifically a Cinnamon colour morph, which gives the bird's head plumage and beak a sandy olive colour. She makes her debut in ONE LAST JONTRON UPDATE!.
In terms of personality, Cinnamon is a lot more aggressive and less aloof than Jacques. During many of her appearances, she is seen biting and being a bully to Jacques. Frequently, she uses her sharper beak to nip at Jacques's cere, which causes him visible discomfort. Despite all of this, Jon has assured that the two birds like eachother, and to put it simply, Cinnamon is the dominant one in the relationship. Her sharp beak has cause Jon distress as well, as he's seen demanding she stop biting him during the update video, and he had a notable bite wound on his nose which he went into detail on during his Counter Strike: The Durst Offensive video.
Unlike Jacques, Cinnamon is not characterized in episodes of JonTron, and very rarely appears in any capacity. She makes an appearance in Japanese Shoot 'Em Ups during the Harmful Park segment where Jontron says that two players can play the game, then gets held along with Jacques where they start shooting lasers. She also appears at the end of Titenic.
In "Jontron Bird Buddies" (on Commander Holly's channel), Jon notes that Cinnamon is the more aggressive of the two, whereas Jacques is nicer. He also adds that Cinnamon and Jacques try to bone each other at times.