Edward A. Schroeder II may have been the only one to attend Sunday school every week, but he also had a wicked sense of humor. Like the time he went to a Halloween party in a Tonya Harding costume, complete with a lead pipe.

“He could be one of your sons. He could be the kid next door,” said his mother, Rosemary Palmer.

Schroeder, 23, of Columbus, Ohio, died Aug. 3 when a roadside bomb destroyed his assault vehicle near the Iraqi-Syrian border. A 2000 high school graduate, he was based in Columbus. Heavily involved in his church youth group, Schroeder often volunteered at soup kitchens, was a counselor at Boy Scout camp, a lifeguard and a volunteer emergency medical technician.

“I just remember him always giving back to others,” said Ty Monk, Schroeder’s friend.

“He didn’t pick and choose, either. He did what everyone else didn’t want to,...