did your son provide more than half your living support (think rent, food, clothing, etc); if no , he can't deduct you
did YOU earn less than $4,150? if no, he can't deduct you
there are some other technical rules about citizenship and residency
assuming you could be claimed as his dependent, it would be for the $500 CREDIT for other dependents as there are no longer 'deductions' under the new tax law for dependents
note that 're-portable income' isn't the key test - it's 'support'. so for example, even though you didn't work, you paid all the rent and food from savings, then you probably provided more than 50% 'support' so he could not claim a credit for you (or your other son)
