Castle is a hero trainer on Peregrine Island in Portal Court neighborhood. His coordinates are (-1505, 0.5, -3429.5), and his location is marked on the map as a trainer. He is in the Portal Corporation area in front of their sign.
Born with the ability to create and manipulate Flame, Christopher Thales never had much interest in being a Super Hero. Instead, he focused on his career in politics and public service. That changed when the Rikti invaded though, and since that day, he has been a stalwart defender of Paragon City as Castle!