We’ve been in this situation a few times. Like AN, I believe that you take care of family – that’s part of being family.

The closest situation to yours was when my husbands grown nephew wanted to get established on the west coast. We set the following rules:
– 6 months rent free, after that rent would be $200/month.
– Chores: dinner prep 1 night per week, mopping kitchen floor 1 x week. (Why should the two adults who had jobs do ALL the work… we all contribute.)
– I was not responsible for his laundry – he had to do his own laundry.
– Standard rules that applied to all of us… If you make a mess in a common area – you clean up the mess. Do what you want with your own room.

It worked well for us. Rules and set expectations help everyone involved.