Eclipse started of as an error between the Theater boys, which was later utilized to make a "Safe Mode" a calm even mix of Sun and Moon. This program along with a discarded chunk of Moon's coding where left unused after Sun and Moon separated due to the program technically having its own basic ai it eventually gained sentience, however since Eclipse had not been regarded as its own character it had no memories of its own. When they came to they had genuinely believed themselves to be Moon, until they heard him through Sun, then the realization that they were severed and discarded code set in. For a long time the new-formed ai could not control the body, essentially locked in what the robots refer to as the "mindscape" of Sun, alone with their fear and hurt. From there they grew bitter and angry, when they finally gained the ability to take control they were almost hostile but almost immediately were seen as a villain. They leaned into this title, and as time continued they allowed themselves to be consumed by their feelings, and they would not allow themselves to get attached to others even denying themselves to feel happiness at times as a form of "protection". It controlled his decisions and clouded his mind, it drove everyone way even those who once called him brother or son. He ended up doing things that cannot ever be fully forgiven, he understands that very well.