See if this theory even remotely comes true, I hope the devil helps Julius and not the other way around. In theory of course.
As someone who jerks off Julius to the moon. I already thought about the possibility of this.
Now that we know there are 3 rulers of the Underworld. There is no fucking way there are buddy buddy with each other.
What if Time Magic Devil makes a pact with Julius. He helps him save his kind and he helps him get rid of Lucifero.
Another possbility. Time Magic Devil will be second Liebe. I mean he will be another Devil who dont care about humans that much but he cant say this in front of Lucifero and the others so he gathers power for now to dethrone Lucifero.
Look. Julius's disappearance during the most important arcs in the show was never explained he also knows transformation magic.
What he was doing when he was out of the Kingdom? Literally never explained.