Jadyn is a "Minor Character" on TheMewx, and he appears to be wearing a light grey jacket with a light green shirt, black shoes, and dark blue pants. Ethan actually drew him (with the help of Jadyn) (seen in the picture below). Ethan did mention that Jadyn might appear in the Christmas special, and not much more is known at this time.
He's animating a short.
The Tale of Jadyn and Ethan on That Day When They Took Out The Trash