Knuckles the Echidna is Sonic's stubborn yet will-hearted friends that always searching for the chaos emerald to return to rightful place at angel island, he become Society's scouting unit which is on team Sonic.
Knuckles lives on Angel Island, which hovers in the sky thanks to the power of the Master Emerald, which he is charged with guarding. Knuckles is the last surviving member of the Echidna people who once inhabited the island, though it is later revealed that he is not the last of his species entirely. Due to his rather remote location and the fact that he rarely strays far from his duty, Knuckles is often alone, and as thus can be quite antisocial and distrusting, but on the other side, he is often quite gullible. One example of this gullibility is the belief that he held throughout Sonic the Hedgehog 3 that Sonic and Tails were attempting to steal the Master Emerald and that the infamous mad scientist Dr. Eggman was trying to protect it.
Dr. Eggman, of course, had lied to Knuckles, and was planning on using the emerald to power his space station, the Death Egg. In the Hidden Palace Zone, Robotnik's betrayal was revealed to him very bluntly, as Dr. Robotnik had broken into the Master Emerald chamber. Knuckles gets zapped, and realizes that Sonic is on his side. He helped him by going to the Sky Sanctuary (by smashing walls that blocked a transporter module). After teleporting to the location, he then activated the bridge that allowed Sonic to get farther into the Sky Sanctuary, but was unable to help him any further due to exhaustion.
After the Death Egg was destroyed and the Master Emerald was secured, he saw Sonic and Tails off, presumably feeling gratitude.
Appearence in UltimaEdit
Knuckles appear mostly on the Chaos Emerald arc while searching for the Emerald all over the multiverse. it is unknown which his series incarnation come from, but mostly mixture from the games and Sonic X series.