Not sure how long your veteran roommate has lived with you--you do not say. There is a possibility you could get the $500 credit for other dependents for him--that is all, if you can even get that. If you claim him, be aware that a person who is claimed as a dependent does NOT get the $1200 stimulus money.
CREDIT FOR OTHER DEPENDENTS
https://ttlc.intuit.com/questions/4499708-what-is-the-500-credit-for-other-dependents-family-tax-cre...
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