Okay so I'm going give you guys a "small" piece of what it could be like. Afterwards you'll see an overview of the rest of the film.
Okay so here's how it could happen...
The beginning of the film features Superman coming to a military base at the request of General Swanick. The general introduces him to Lex Luthor who has not only helped in rebuilding Metropolis but also in military production. Lex immediately takes the chance to welcome Superman and asks for his help in finding an individual that has been problematic. A vigilante known as "The Batman."
Lex and the general talk about their need for Superman's help due to the fact Batman is destroying their military facilities in Gotham that will help fight off against any future alien threats and to stop him from sabotaging his company, considering Lex's company is helping Metropolis being rebuilt. After convincing Superman agrees.
After the general leaves Lex pulls Superman to the side and asks, as a scientist, if he can know the location and access of his ship for research and "for the betterment of mankind." Superman isn't so easily swayed until Lex mentions Emil Hamilton was not only a co-worker but a friend, to which Superman eventually agrees. (I know it sounds stupid and cheesy but remember "Superman: The guy who sees the best in everyone.")
Afterwards, Superman uses his disguise as Clark to work "undercover" and arrives at Gotham via plane. Gotham is presented as a very Gothic and dark city.
Clark acts as a reporter of the Daily Planet to write a story on the happenings of LexCorp buildings and facilities in Gotham. At a LexCorp facility Clark and other press are able to interview Commissioner Gordon about these incidents involving "The Batman" and a mysterious individual who killed three people with guns and blades. The Commissioner declines to comment. Clark gets a chance to talk briefly to LexCorp's business partner in Gotham, Bruce Wayne, who seems to be happy to work with Lex to help rebuild Metropolis.
During the night Superman is able to fly quietly and unseen throughout Gotham, disposing of any criminals along the way(without lethal force). He flies around many LexCorp buildings looking for any sign of Batman to which none can be found until one facility across the edge of town is caught on fire. Superman flies to the facility and puts out the fire only to realize the building is an outdated and abandoned LexCorp building.
Immediately a LexCorp building on the other side of town(the one he was near before) blows up and is demolished in an astonishingly perfect way(just like those Las Vegas casinos). Superman flies to the building and tries to stop the rest from falling but can only save the ground level. He searches the entire place to find anyone but instead finds people(security and workers), tied up or unconscious, underneath ground floor safe and sound.
Superman makes his way into the inside and helps the people to which they keep telling him "The Batman" was there and point to an exit door. Superman follows the exit to a forced opening above which leads him back outside and immediately a Batmobile.
Superman immediately flies in front of the Batmobile and stops it dead in its tracks without trying. Superman forces the opening of the car and finds no one inside! He then hears a small "ping" ringing faster and faster until an explosion erupts within the car. Superman is on the ground dazed and quickly gets up and flies high in the air and uses his vision to see Batman running on rooftops while using his gliding cape and grappling hooks.
Superman flies towards Bats, trying to swoop in and grab him but Batman backflips into the air and lands his feet on Superman actually pushing him into a building while Batman, still in the air glides into the building where Superman is and lands. He takes one of many viles from his belt buckle, filled with clear fluid, and breaks them on his knuckles. Before Superman gets up Batman lays many well hit punches before Supeman can react which actually hurts him to the point of making him bleed.
Batman grabs Superman by the neck and pulls him close(This is where we actually see his face for the first time) and says, "Stay out of Gotham!"
and tosses him on his back. Superman gets up and sees Batman has vanished.
So that's a "small" detailed description of what it can be like in terms of tone and setting.
So since typing the rest would take forever here's an overview of the rest of the story:
-Batman and Superman fight again.
-They both come figure out their identities and eventually(with talking) become allies.
-Batman tells Superman he became suspicious about Lex after Batman was attacked by a merc on Lex's payroll. (Flash back footage of Deathstroke and Batman shown)
-Batman also tells Superman the LexCorp facilities are used to eventually buy out or bankrupt Wayne Enterprises through it's anti-alien military technology. That's why Bruce went into business, to get more detailed into LexCorp.
-LexCorp is also using blood samples from Zod, after the government took his body, to create a liquid based serum(that Batman used) as a weakness against Superman by weapons, soldiers, etc.
-Superman realizes Lex tricked him and that Superman told him the location for the ship(which Lex is shown to already have been there and gathered the info he needed)
-Both heroes make their way to Metropolis and look for Lex and find him at a LexCorp military base with Deathstroke.
-Battle ensues with Deathstroke, laced with the "kryptonite serum," and fights against Superman and Batman.
-Lex surprises Batman and Superman when Lex climbs into
-Batman and Superman battle them both and eventually win.
-Deathstroke vanishes. Lex is put in prison.
-Batman and Superman talk about other people with abilities to which Batman says, "There's a few I'm keeping an eye on."
-Superman asks if anything like this or even worse happened again if he and Batman wanna join forces to stop it. Batman says, "We'll see."
-End.
So that's it guys. Let me know what you think in the comment section below..
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