Complete Monster: Jacinto. at first seems to be just a nasty jerk who cheats on his girlfriend with his teacher, but the truth is different. Jacinto, in his greed and lust for gold, is revealed as the murderer of the ghost boy Santi. He later blows up the orphanage and murders his own girlfriend without a twinge of remorse before trying to kill the other boys as they lure him to Santi's vengeful spirit.
Harsher in Hindsight: Carlos and Jaime are seen again briefly as young guerilla fighters in Pan's Labyrinth where both are killed by Captain Vidal and his forces, showing just what little of a future they really had. Guillermo del Toro confirms that it indeed is them.