In the comics, Knuckles is born to parents Locke and Lara-Le, and is next in line in the Brotherhood of Guardians (a long line in the echidna heritage of protectors of the Master Emerald). His parents, who argue much about how Knuckles should be raised (Locke, who was the Guardian before Knuckles, believes Knuckles should fulfill his duty of Guardian, while Lara-Le just wants him to live a normal life). His parents, arguing frequently and eventually getting a divorce, leaving Locke to take care of the young Knuckles, leave an independent attitude on Knuckles. The story can not be trusted in its entirety, however, since in the games, Knuckles (although he is Guardian of the Master Emerald) is the last of his kind (or tribe, according to Tikal's story in Sonic Adventure), having no other living relatives. The differences between the comics and the games should get a little more speculation, but for now is considered non-canon to the Knuckles that appears in the games.
Sonic the Hedgehog 3Edit
His role in Sonic 3 mostly consists of being a nuisance to the two heroes, Sonic and Tails. He first makes a startling debut appearance by interrupting Super Sonic on his peacfuel glide to Angel Island, and then snatching all of the Chaos Emeralds before the hapless hedgehog can recover. Tails eventually accompanies Sonic after getting out of his bi-plane, and Knuckles makes yet another appearance in Hydrocity. Whereas Sonic and Tails just want to make it to Eggman in one piece, he stops them by breaking the bricks, and the two are stuck with a longer route. This is because Knuckles, who would do anything for Angel Island's precious Master Emerald (as he's the Guardian), was tricked by Eggman, who told him that Sonic and Tails wanted to steal the Master Emerald. At the end, Knuckles eventually attempts to stop Sonic riding in Eggman's former Eggmobile, but to Sonic's relief, falls over due to the mass destruction Eggman caused to his home-island. Knuckles still doesn't see Eggman's plan as Angel Island continues being pulled apart by Dr. Eggman, who knows there's a lot of power to the Master Emerald. He would appear in the game's sequel, Sonic & Knuckles, where he'd finally catch a clue as to what's really going on.