Metallo could be a main villain in the sequel. A human - turned - cyborg, he has a kryptonite power source which gives him an edge against Superman. His hatred for Superman, combined with his enhanced strength and weaponry, could make him a formidable adversary. He could be created by Lex Luthor as a weapon to finally defeat Superman once and for all.
Darkseid could also be a main villain. He rules the planet Apokolips and is one of the most powerful beings in the DC universe. If he sets his sights on Earth, Superman would be the first line of defense. Darkseid's Omega Beams and his army of Parademons would make for an epic battle against Superman.
Brainiac would be a great choice. He's an incredibly intelligent and powerful alien with a thirst for knowledge and a disregard for other life forms. He could come to Earth to collect data and specimens, seeing it as just another planet to add to his collection. His advanced technology and strategic mind would pose a huge threat to Superman.
Lex Luthor could be the main villain. He's a classic Superman foe and always has some devious plans to take down Superman.
One possibility could be Superman facing a new and more powerful alien threat. Maybe an entire race of super - powered beings come to Earth, believing it's a strategic location for some intergalactic reason. They could have powers that even challenge Superman's, forcing him to learn new ways to use his own abilities and seek help from his human friends and allies on Earth.
Lex Luthor would be a great choice. In Smallville, he was a major adversary of Clark. In a combined fanfic, he could get his hands on some Kryptonian technology from Man of Steel and become an even greater threat.
It could be a new villain that emerges from the power vacuum left by Thanos. Maybe one of his underlings decides to step up and continue his tyrannical ways.
The main character is Superman, also known as Clark Kent. His adoptive parents, Jonathan and Martha Kent, are also important characters. They play a crucial role in his upbringing and shaping his values. And of course, there are villains like General Zod who provide the conflict in the story.
It could be the Green Goblin. In the sequel, he could return more powerful and with a new plan. Maybe he has found a way to enhance his strength and insanity using some new Oscorp technology. He could target Spider - Man not only for revenge but also to prove his superiority over the web - slinger.
It's more likely a sequel. 'Real Steel' was a well - known movie, and adding '2' to the title is a common way to denote a continuation of the story. A prequel would usually have some sort of indication in the title that it's set in the past, rather than just a number increment. So, all signs point to it being a sequel.
The children of the original couple. They could inherit the charm and the values of their parents in terms of love and relationships.
The Green Goblin is one of the main villains. He has his own set of powers and is always causing chaos in Spider Man's city.
The Green Goblin could be a great main villain. Imagine he somehow gets hold of time - travel technology too. He could go back in time to eliminate Spider - Man before he even becomes a hero, or change events in the past to make his own power even greater in the present.