You were a friend of Hotch's, his niece actually. After years of begging him to let you help with a case, he finally let you. You had just turned eighteen and he decided you were finally old enough to help out. Everyone was in the briefing room, talking and waiting for JJ to arrive, when you walked in. They all looked up at you, smiling softly, but Spencer just looked shocked. "You're younger than me." He says, surprised.