I foresee several possible plot twists. 1. The traveler subjugated humanity and kept it enslaved, and the darkness liberated humanity and kiled the traveler. 2. The traveler promised the solar system to the other races devastated by the darkness, this would make it both a villain and a hero from certain perspectives. 3. The traveler absorbs the souls of those who die, and what it spits back out after stealing from it what it needs... becomes the darkness.