Okay so in order for that work, he’d have to stay with my Xbox as his home account
This is how it works, you log in to your profile on his Xbox and then you go to settings.. profile...then somewhere in there you can set the Xbox to be your "home" Xbox.
Now whatever games you own he can play, he can even go online.
Now back at your house, when you login you have access to your games no matter who's system you're on..So you can play your games no problem just as long as you're logged in with your profile.
Another way to do this is for him to sign you in on his Xbox, then he can eat. Only problem with that method is you gotta be logged in for him to eat and you couldn't play at home online while he's doing that.
Finally to piggyback off of step one if you have him designate your Xbox as his home Xbox you'll get access to whatever games he buys. Your welcome...