One of my favorite video games is Injustice Gods Among Us. Ever since I played it I can't stop thinking about the character Ultraman Superman's evil Doppleganger and leader of the Syndicate. I feel like he should be reintroduced and with some tweaking and alterations I think he could be a very compelling character. How I'd re-do him is I'd have him possess all of Superman's powers and weaknesses. Essentially I have his back ground be the same but include differences like his ship after crashing on the Kent Farm caused so much damage it ruined the Kent's Financially causing Johnathan Kent to become an alcoholic and very abusive. Creating a situation where Clark finally fought back but accidentally murdered his Johnathan with his super strength and maybe even accidentally killing Martha with his heat vision.
Ultimately these events cause him to seek out his true lineage and he fully embraces his kryptonian heritage rejecting the name Clark Kent and going only by Cal El. Around the same time his Zod breaks free from the phantom zone and becomes like a father figure to him molding his ideology and beliefs only Zod gets killed by a weapon(possibly designed by his Earths Lex Luthor) using kryptonite and Cal El grows even more unhinged.
Realizing he can't openly conquer his Earth he creates two personas Superman(to give the people hope) and Ultraman(his true personae that gives the people something to fear) which could be where his Lois Lane comes in she could be that beacon of light that keeps him from being a monster and just when he starts thinking he could be a hero for real she gets killed and he completely goes over the edge and fully embraces his Ultraman personae believing humans little more than animals that must be controlled.
Essentially how I'd do his first encounter with Superman is I'd have him pose as his Earth's Superman as a subtle deception leading up to the shocking reveal and for his main goal being to make himself immune to kryptonite. I like this idea because I think it would add a lot of complexity to the character Ultraman and it would be interesting to see his how Superman would react to a version of himself that is completely messed up. I was pretty much inspired by Flash Season 2