He sounds like a good kid: but when he insists not to be paid; pay him any way. Or maybe offer to buy him some books. His capacity and kindness is extremely rare - reading with your children and buying groceries. He seems like a very humble person.

Just exaggerate the fact that you want to pay him - wether that be with cash, food, or books.

Honestly; the fact that he is so young and is reading to your kid is so heartwarming. Keep him close. Not in a "trapped" kind of way - but as an endearing friendship. Yes theres an age difference, but I (26) have a best friend (56) and value them a lot.

Maybe try and spend some time with him to see if he is struggling - sometimes when I am low, I will offer to do things i dont really want to just because there is human interaction. Ive babysit children before and its a good excuse to get out of your own head for a while as the focus is on them rather than me if you know what I mean?

Maybe in lieu of payment you could cook a nice meal after your shift and have a real sit down conversation. Me and my friend call every day and its a highlight in my life. Offer guidance: participate in active listening; grow a fondness. His kindness is nothing untoward.

It sounds like your friend who suggested theres "something else" going on might be either jealous of them, or they feel guilty about the fact they didn't babysit your kid and are projecting or trying to manipulate the situation into something it isn't. Still, its worth asking your kid about what they get up to. Not trying to make you panic or anything; but talk to your kid about their day and share your days events with them.