He was voiced by Tim Matheson.
As an adult, Brad's hair has gone from blond to gray/white. Brad wears a big white coat with two green pockets on front and sides and a a sea green high neck and white pant. Brad's chin resembles Fred and became Fred's double after undergoing plastic surgery. Professor Pericles refused to undo the surgery, so he was stuck with this appearance to the end of his life (until the reset).
Brad always thanked his wife Judy Reeves every time she volunteers a detail whenever he speaks. Brad seemed unemotional after getting together with Fred and gets angered whenever Fred doesn't want his help. Brad and Judy joined Professor Pericles to get the pieces that Mystery Incorporated has. Brad was willing to steal from Fred and even try to kill him until the timeline was altered.
Brad Chiles led the original original Mystery Inc. before leaving town after Fred Jones, Sr. and Professor Pericles blackmailed them with falsified documents implicating his parents in criminal activity. Brad married Judy and gave birth to a child, however Fred Jones Sr. captured the baby son as the Freak of Crystal Cove and swore to harm the baby unless Brad and Judy left. Fred learned the truth and eventually went looking for his parents.
Brad and Judy cleaned Fred's place and admitted to the Mystery Inc gang that they didn't return for Fred earlier on because Mayor Jones threatened "bodily harm" to him. They even attended a party in their honor at Daphne Blake's mansion before joining Professor Pericles and Mr. E to find the treasure. While that, Brad and Judy offered to help Fred capture Hebediah Grim, and were offended when he turned them down. Eventually they did help, and their traps were a complete success. Brad and Judy started to try to steal and kill Fred to get their hands on the treasure. Those two even burned down City Hall and murdered Hot Dog Water.
Brad and Judy helped Professor Pericles and Mr. E locate the gate to the Evil Entity while being unhappy about their new appearances. Brad mocked Judy's aged appearance and she mocked his new face. Brad and Judy offered to serve the Evil Entity and they were devoured by it.
In an alternate timeline, Brad and Judy are wealthy obstetricians who raised Fred in their home which was in the Jones mansion. They never underwent plastic surgery and Judy still added details when Brad spoke, which he thanked her for.