Ulysses King was a professor on Olympus, the original Earth. He was in charge of the dissertations on alternate realities. In essence, when an Olympian (and this includes Ulysses King himself) wanted to create a new reality, Ulysses was the one who would create that new universe. He fled Olympus when Marcus Darwin and the Carnifex tried to steal NotTA (Notional Transfer Apparatus). In the initial explosion Ulysses’ wife Penelope was killed and Ulysses fled blindly into foldspace (the dangerous region between alternate realities). Now he’s a renegade and a wanted man.
NotTA is the only device in existence that can transport more than person from any foldspace ascension point to any other ascension point. Ascension Gates can transport more than one person, but they are limited to one spot in each reality and require large amounts of energy. NotTA can go anywhere at any time (if she’s recovered from travel). The Olympians want NotTA for their own ends and Ulysses wants to make sure they don’t get their hands on his creation.
Ulysses King has developed a fondness for the beings of these different realities. He’s still a little arrogant and his moral compass doesn’t always mesh with Jake or Crystal’s. Unlike most Olympians, he no longer sees the residents of different realities as playthings. He now spends his time traveling from world to world trying to stop the machinations of his own people.