When her brother, Aaron, was serving in Iraq, 20-year-old Rachel Seesan used to laugh with him about the castles he built there. “When I last talked to him on the phone, he was joking to me about how he used his hard-earned engineering skills just to build sandcastles in the sand,” she said. “That’s just something we joked about.” She was not alone in her fond memories of Army 1st Lt. Aaron N. Seesan, who died Sunday from injuries he received while fighting in Iraq. He died of burns he received Saturday after a roadside bomb exploded and set fire...