Additional notes: There is no need to report rental income or pay rent, family can live together without filing a mess of tax paperwork. You might qualify to claim him as a dependent, especially if his medical needs grow, but you are not required to do so even if you could. If you pay more than half his total financial support, you would be allowed to take a medical expense deduction for his medical expenses that you pay, even if you don't claim him as a dependent.
Whether or not you claim him as a dependent or charge him rent has nothing to do with where his domicile is located.
