Ecco is the Sinister Sibling in charge of the fourth Dungeon Level, and Communications. His associated colour is pink and Cain likes to send him prank calls because of his gullibility. He talks through huge speakers arrayed around the Dungeon Level.
Ecco also was the Sibling responsible for decrypting the Code, a (theorized) part of the Angels' communications, which sends signals throughout the Dungeon Levels.
So far, two Transmitters/Recievers have been seen, one in the Greens, and one in Proxxy's Boss Room. However, during Spirit Duel, Brawler Mouse(Transitory ReAwakener), has also intercepted one of these signals.