Ultima is a being that is one of the 3 Remnants, similar to Reginous. There are two variants of him in the story of EONS, the proper instance is in the main timeline, where he met Jacob and bound to his presence to unify their powers, this granting Jacob pyrokinesis.

The second instance is during the alternate timeline, where he never met Jacob and stuck to his roots as a Remnant... Conquering. His reawakening after eons of slumber caused his power to weaken as he hadn't been active for a long period of time. As he sensed a great energy from Charlie from light years away, he knew he was special, the key to regain his power and more. He didn't know what he was, but every Charlie in any timeline is qualified and categorized as a "catalyst," a being that can manifest the good and the bad depending on whom manipulates the individual's essence. This leading to Ultima forcefully binding to Charlie's presence and masking his essence and became (Charlie Based) Ultima.