That's complicated. To be your dependent, he must meet of bunch of tests that @DoninGA posted, but I'm going to focus on the "must live with you more than half the year" test.
Because, even if he lives with you, his parents may also be able to claim that he lived with them more than half the year. He can be considered to live with his parents if he would have lived with them and was away for a "temporary absence"--and education is considered a temporary absence.
So if he would normally be living with one or both parents except for college, then that parent can probably claim he "lived with them" and claim him as a dependent and claim his expenses. If you also claim him, I don't how the IRS would rule on the dispute--would the parent win, or would the aunt where the child actually lived win?
If there is no other person who could might try to claim him as a dependent, such as a parent, then no problem. But if the parents are involved, you might need to have a conversation with them before you file, because if you both claim him, you will both be talking to IRS eventually.
