Miguel Diaz was a boy from Gotham City.
Miguel was trapped in a fire, and Batman had to save him. But Miguel was terrified, as Batman bore resemblance to a monster, and the only way for Batman to gain Miguel's trust was to briefly unmask himself to show that he was indeed human.
Kobra caught up on the news that Miguel had seen Batman's true face, and kidnapped him in the hope of discovering his secret identity. They used a synaptic sensor to read Miguel's memories, but could not get an actual image, as the image they pulled from Miguel's memories substituted the features of the fictional "Soldier Sam" character for Terry's, meaning that the image Kobra obtained was, in reality, useless. Terry deduced that Miguel must not have gotten a good look at Batman, and his mind constructed the idea that Batman was a hero a la Soldier Sam.
Batman saved Miguel, who was able to get along very well with his life. When all was over, Max and Terry met at Miguel's school. Terry was confident that Miguel didn't remember what Batman really looked like. However, as Terry and Max walked away, Miguel glanced over his shoulder with a knowing smile on his face--from this, it can be assumed that he does realize who Terry really is, but that Terry's secret is safe with him.