Knuckles is a red echidna who protects a powerful jewel known as the Master Emerald. Knuckles is a very vital part of the Sonic the Hedgehog series. He is great friends with Sonic and he often helps him find the Chaos Emeralds. He was originally a rival to Sonic after he was fooled by Dr. Eggman. He is called Knuckles due to having large, protruding knuckles on his hands.
At times, Knuckles has a short temper, though he is very loyal, and a dependable friend and ally. He has a rivalry with Rouge the Bat, ever since she first attempted to steal the Master Emerald from under his nose. However, Knuckles mainly searches for Master Emerald pieces when it breaks (sometimes, he even breaks the Emerald to avoid having it being stolen).
First appearing in Sonic the Hedgehog 3, Knuckles was tricked by Dr. Eggman into being Sonic's enemy. In Sonic & Knuckles, Knuckles soon realizes that he was tricked and helps Sonic get to a hard to reach area in the game, there for allowing Sonic to reach Dr. Eggmans space station, the Death Egg, and defeat the crazed scientist. He is tricked again, in Sonic Adventure DX, but after he finds out he has been tricked again, he finally joins Sonic's team in Sonic Adventure 2: Battle.
A powerful red echidna also known by his full name, Knuckles the Echidna. Knuckles resides on Angel Island, where he guards the Master Emerald. Both friend and rival of Sonic, Knuckles is a martial-arts expert who can break through rocks with his spiked fists. In addition, he can climb walls and use the wind to glide through the air.