After appearing as a short-term sidekick of Tony’s, what does the future have in store for Harley?
When we first saw him in Iron Man 3, Harley might have barely been in his teens. He met Tony Stark, aka, Iron Man, when he broke into his garage, seeking shelter from the cold. Harley decided to team up with Stark, despite his continued refusal, for taking down the Mandarin and stop his terrorist activities. Teaming up with Stark brought him his fair share of troubles, but he stuck to him nonetheless and took care of his Mark-42 Armour while Stark went on a solo mission to the Mandarin’s estate.
It was evident when we saw him during Stark’s funeral in Avengers: Endgame that he had stayed in touch with the boy throughout the years.
In the MCU Wikia, it has been stated that Keener sees Stark as a father figure since his own father abandoned him when he was four.
Harley is quite smart for his age and has built his own potato gun to ward off intruders. Tony even complimented him on his skills. He didn’t give Tony any special treatment but simply treated him like how a friend would. He helped in restoring his damaged armor and gave him ideas on how to fight against A.I.M. and defeat Aldrich Killian.
Towards the end of the movie, we can see that Tony rewarded him with new equipment and turned his garage into a mini version of Tony’s work station, complete with computers, robotics, and a Potato Gun Mark II.
The actor who played Harley, Ty Simpkins had signed on a three-picture deal with Marvel. We can’t say for sure if he’s ever going to return for the role.