Doctor Finitevus was an everyday red-furred male Echidna scientist for the city of Albion, who was in charge of creating a Chaos Siphon Suit to absorb Knuckles' Chaos powers when deemed he was a threat to everyday Echidna life.
When push came to shove, Knux was too powerful for the suit, and Finitevus ended up absorbing the collected energies instead, changing him physically (white fur) and mentally (insane). Though he had become mentally unstable, his intilligence rose greatly. And he had become stronger and faster as well. At first nothing seemed wrong until he started "voicing" his complaints on Mobuis. He saw that the world was corrupt and set about finding every way possible to 'cleanse' it in a 'bath of fire'. Thus, the Albion securituy team put him in captivity and was to be executed, but He escaped using his newly invented warp rings he had made using his corrupt chaos control.
After his escape he quickly sided with the dark legion, becoming their, Techno-mage. Once angel island was free, he gave albions quardinates to the eggfleet who proceeded to burn it down.
Dr. Finitevus debuts in Sonic Adventure 3: GX as one of the four main villains of the game, and the main antagonist in Knuckles' storyline. In the game, he leads an army of hooded Echidnas called the Dark Legion and is in search of an ancient suit known as the Enerjak suit, which was hidden by the Brotherhood of Guardians in order to never be found and used for evil purposes. This suit allows the user to gain immortality and gain unimaginable powers out of this world. Thus, Knuckles is the only one who knows where the suit is hidden. Finitevus also teams up with Dimitri, a mysterious floating head whose true intentions are unknown, in order to beat Knuckles in this treasure hunt.
Dr.Finitevus's secret identity is Knuckles the Echidna.He dressed his brother like Knux for when Knuckles and Fini are at the same place at the same time.Knuckles can transform into Dr.Finitevus by speaking his Corrupt Chaos Chant and it works the other way around.Both Rouge and Scourge know about Finitevus's secret and have kept it silent since.