The same thing happens to Littel John as to my clients in the different activities to which I dedicate myself. When you give them a product or service for free, they don´t value it. It is the same example that you put of the children that the more they receive, the more they want but the less they thank.
The problem you have now with Little John is that you misused it to receive the money without demanding anything in return, he assumes he deserves it, if you stop giving him the money, for him the bad guy will be you. I think that as you already adopted it, now you must put it to do something, maybe deliver some merchandise to sell or give some task in exchange for money, not the money without the counterpart.