Geno

Jay Capper Chungus AKA Geno, is Jay Capper Chungus from an alternate timeline that has been destroyed.

History
Sometime before the events of Big Chungus- or, technically during them, this reality's Jay was murdered by Elmer.

Instead of being dead forever, Jay somehow woke up in an empty universe as a semi-ghost.

It is unknown why his name is Geno or how he met Ink or Error, but it's likely that since Geno is based off of Geno Sans, his name has something to do with Genocide.

Geno can be found in the Plains if the player has a certain X value. This event, however, appears to not be canon.

Geno first canonically appears after waking Ugandan Chungus from a nightmare. He turns invisible and follows Ugandan Chungus and Jay until they and their other party members are killed by the Core Of Darkness.

He informs Jay that Ink and Error can use their powers together to Overwrite his Universe.

He also tells Jay that they may meet again.