I would like to purchase the new Batman DLC (Season Pass) with my profile's PayPal account for my son's profile. Can that be done? Thanks in advance.
If your sons profile is signed in on the console you purchased the dlc on (or is set as your home console on the Xbox One) he will also be able to use the DLC.
Yes, as long as your profile is on the same console. He should be able to use any DLC that you purchased. If it doesn't allow him to use it, then you will need to license transfer your account to your "Home" Xbox.