Chaos was the guardian of the Master Emerald several years ago. Then one day, Tikal's father tried to take the seven Chaos Emeralds to defeat their enemies. Chaos, enraged, killed all of them and was imprisoned in the Master Emerald.
Chaos was imprisoned by the Master Emerald for several years, until Doctor Eggman destroyed it and set Chaos free. A piece of Chaos was subtracted and swallowed by Froggy, who stole the Purple Chaos Emerald. Later, he sees Cheese, and Chaos attacked Station Square and was fed the Yellow and Red Chaos Emeralds by Dr. Eggman. After being defeated by Sonic and Knuckles, it left.
Later, Sonic and Tails found the Cyan and Green Chaos Emeralds, but Chaos 2 swallowed them up too, becoming Chaos 4. He was recalled by Eggman and then ate Christopher Thorndyke, Big, Froggy and Lily's Blue Chaos Emerald, becoming Chaos 6. Knuckles and Sonic defeated him, but in episode 31, he attacked Eggman and then absorbed the White Chaos Emerald, becoming Perfect Chaos. Chaos then destroyed Station Square, letting all the Chaos Emeralds, drained of their power, go and they were gathered by Amy, Cream, Chris, Big, Knuckles, Eggman and Tikal, who had traveled there from the past. Sonic used them to become Super Sonic and defeated Perfect Chaos. After he returned to Chaos 0, Tikal took him home.
Chaos 0Chaos 2Chaos 4Chaos 6===Chaos 0Edit=== Chaos 0 was Chaos' true form. He used it to destroy Tikal's father, and also in Station Square until Eggman fed him the Yellow Chaos Emerald, transforming him into Chaos 1. He later took this form again when Perfect Chaos was defeated and he regained his sanity.
Chaos 1 was the first form Chaos took. He fought Sonic and Knuckles until Eggman fed him the Red Chaos Emerald, transforming him into Chaos 2.
This was the second form Chaos took, until Sonic and Knuckles defeated him. Eggman then recalled him. He later absorbed the Cyan and Green Chaos Emeralds, transforming into Chaos 4.
Chaos took this form when Tails dropped the Green and Cyan Chaos Emeralds, becoming Chaos 4. He then battled Tails and Sonic until Eggman recalled him. He later absorbed the Purple and Blue Chaos Emeralds, becoming Chaos 6.
This was the fourth form Chaos took, when he absorbed the Purple and Blue Chaos Emeralds. He nearly defeated Sonic and Knuckles, until Knuckles destroyed his brain and destroyed him. However, he survived and later attacked Dr. Eggman, taking the White Chaos Emerald and becoming Perfect Chaos.
Perfect ChaosThis was Chaos' final and strongest form. He absorbed the White Chaos Emerald and became Perfect Chaos, flooding Station Square. He let all the Chaos Emeralds go and were gathered by Sonic's friends, and their friendship helped restore the Emeralds' power. This allowed Sonic to become Super Sonic and defeat Perfect Chaos, returning him to Chaos 0.