The BRTE-500, also known as Bertie, is an A.I. unit created by DARPA.
Bertie was created by Zack Weinberg and followed him around the camp like a loyal dog. Shane Schofield also liked Bertie and was made Bertie's secondary buddy, in case something happened to Zack. Bertie was good at chess and alwys beat Schofield at it. Mother is reluctant about Bertie at first for fear that he may turn on the camp dwellers, but Bertie had been programed with a friend database and was under order never to harm anyone in the friend database.
When Schofield and the Marines at the camp were called to stop the Army of Thieves on Dragon Island, Bertie accomapnied the team to the island and was blown into the surrounding water by an RPG missile. After a while, Bertie managed to reach the island again and went in search of Schofield, finding him right after he had been electrocuted and killed.
Bertie used his built in defibulator pads and restarted Schofield's heart and helped him rescue Mother, Zack, and Baba but was damaged in the process by another RPG. Bertie was straped to Schofield's back as he went after Marius Calderon, Typhon, and Vittorio Puzo who had recently betrayed the team. Schofield ran out of ammunition and killed Puzo instead since Schofield had erased Puzo from Bertie's friend database.
After the army was defeated and a nuke was on its way, Schofield and Bertie went around the island, gathering up Zack, Emma Dawson, and Veronique Champion. They reached a bombshelter on an adjacent island a second short of the nuke's impact and were later rescued.
During a celebration ceremony at the White House, Bertie was present a rebuilt by Zack. Zack later showed Bertie off to the President.