Illinois law provides that service on individual defendants "shall be made 1) by leaving a copy thereof with the defendant personally, or 2) by leaving a copy at the defendant's usual place of abode, with some person of the family or a person residing there, of the age of 13 years or upwards, and informing that person of the contents of the summons, provided the officer or other person making service shall also send a copy of the summons in a sealed envelope with postage fully prepaid, addressed to the defendant at his or her usual place of abode, ..." 735 ILCS 5/2-203(a). Illinois law also provides that, if the plaintiff is unable to obtain personal service on the defendant, then "the plaintiff, his or her agent or attorney may file an affidavit stating that the defendant . . . . on due inquiry cannot be found . . . ." 735 ILCS 5/9-107 . That is necessary to proceed to service by publication.
Tell your roommate about the encounter.
Have your roomate retain a lawyer .
As long as you are over the age of 13, since you reside in the same household as your roommate, service is proper. You would do your roommate a service by making sure he gets those papers.
Tell you roomate to get a lawyer and not play cute with the service issues. The answers above are quite accurate.