Numbuh Infinity is a mysterious high ranking member of the KND. He agreed that they're will be a treaty with the teenagers. Numbuh 1 was furious with the treaty and wanted to have a word with him. Suprisingly Chad was attacking him in his office and Numbuh 1 captures him. Infinity then orders Numbuh 86 to take Chad along with Nigel to Arctic Prison. Luckilly they escape and the rest of Sector V think Numbuh Infinity is selling the KND out to the teenagers. When the treaty is about to commence the teens play a massive racket that nearly deafens the kids until Nigel and Chad crash down. Then one last battle between the kids and teens starts. It turns out Numbuh Infinity didn't know the teenagers double crossed the kids. Then Numbuh 48 is attacked by him along with Numbuh 2, 3, 4, and 5, to be stopped from destroying the carrier with all his chocolate. When the ship breaks, it is rebealed that Chad was still on the KND's side. Numbuh 274, and Infinity dissapear to the Teens Next Door base.
Numbuh Infinity has ulterior motives as he was responsible for the events during the sixth and final season.
Numbuh Infinity is technically not a hero; as he framed Numbuh 1 for treason, manipulated him into joining the Galactic Kids Next Door and was the one who imprisoned Chad at the GKND headquarters.
He might be second-in-command of the entire Galactic Kids Next Door and will eventually become the secondary antagonist of the upcoming sequel series.