They still compete.
He doesn't think they'll ever stop.
It's… a part of them, just like Adam and Sarah. Sometimes it's about the most mundane things: who can drink a cup of water the fastest, who can levitate the longest (this was stopped after they both fell unconscious) and the like. Sometimes it's a little more… personal. How many times can they make the other… well, Josh always said he was a prude.
Often it's during training, such as who can run the most laps around the forest track? Or lift the heaviest weights?
Sometimes it's mental, like who can hack into the Pentagon the fastest? Or whose money can she steal? (He always makes her give it back.)
He'll never admit it, but he loves the thrill when he beats her. He loves the look on her face, that light, when she beats him. Most of all, he loves her.