Devlin Levin is the future son of Kevin 11,000. Who becomes best friends with Ken Tennyson.
At first he hung out with Ken doing some cool and dangerous stuff in the city. Then he betrayed Ken and used him to break his father out of prison and then Kevin threatens to kill Ken and Max Tennyson. Devlin tells his father they've done enough and then Kevin double-crosses his son and proceeds to kill Ken and Max. Ben 10,000 luckily makes it in time to stop Kevin and he mutates and proceeds into a battle with him and Ken. Devlin later on angered by his father's betrayal helps Ken and Ben defeat him by imprisoning him. He says goodbye but then Max offers him to join their family and he agrees.