Superman: Rising Star (It's a work in progress title)
Background.
This is where the inter-movie continuity would start showing up more, though mostly still in the background, but it would be about hinting at a wider plotline built up over the course of two/three movies.
Plot.
The movie would likely start with some form of crime in progress, maybe a high speed chase or a shootout with police when.
Look, up in the sky!
It's a bir-!
Wait, it's gone!
A blue and red blur starts zipping all over the place and suddenly guns are breaking or being hurled away, get away cars are dropped into the police stations car park or crooks are being piled up at the door of a bank and a bomb is being hurled into the sky or something to that effect. It is mostly from the public's point of view but to the viewers is clearly Superman taking care of business, but not stopping to chat.
After that we see the blur duck into a window, an alleyway, or some other none-descript location and march out as Clark Kent, mild mannered reporter who is a bit late for work but looking like he enjoyed a good jog.
This is where we get to see a bit of his daily life, meeting up with Jimmy, shooting the breeze, then them running into Lois who is already on the case of the red and blue blur. It shows he has a relationship with them, if mostly as office friends, though he's a bit closer with Jimmy and he and Lois snark a bit but it's generally professional, but pleasant.
However, at the scene of his latest daring so, Superman overhears some people talking fearfully or angrily about the red and blue blur, something he's been picking up on a bit more of lately. Others are happy, and some are very happy, overly so, like they're reading 'god is being active now maybe he'll get rid of those rowdy kids' happy.
Suffice to say it kills his buzz a bit and we get to see the profile the Daily Planet is building on him and the public perception of his actions so far. It is largely positive but layered with a dose of 'WTF is this?'
Once night fall hits he either swings by the Fortress of Solitude but finds his father's AI cannot offer much on the subject, and we get a look at the fortress and also some of Kal-El's "I'm not human" sense of alienation. However he doesn't dwell on it too long, instead opting to go see his parents exclusively as Clark Kent. (I find the distinction Clark draws between 'Clark' Reporter Clark Kent, Superman and 'the last son of Krypton' interesting and would try to work it in subtly.)
Taking inspiration from the animated series his parents advise that A, if he doesn't want to be Superman he shouldn't, but if he thinks he's doing the right thing he should be less secretive about it so people don't end up misconstruing his actions. He agrees but doesn't want to reveal his identity, both for his parents sake and because "I'd go crazy if I had to Superman all the time". (I did say I was taking inspiration
Thus he ends up dropping in to see Lois Lane and Jimmy and gives an interview to explain what he knows of his background, his motives and what he's doing. Namely, fighting crime and helping out in disasters (stopping a train from falling off a broken rail way, that kinda thing) because it's the right thing to do and that he doesn't really want anything save for people to know that he's here to help. The story hits the news, people are excited, Superman starts letting himself be seen more and gets a bit more of a 'friendly' persona by doing some more minor but still good things and is riding high. So naturally this is where the wheels come off.
Background.
Lex Luthor would not be the main villain of this story. Or more accurately, he would not be the prime and direct threat to Superman. Why would he? Superman hasn't done anything to offend him yet or screwed up his works. Yes he might be a bit bugged by Superman's powers but he's not the first 'metahuman' or alien Lex has heard of given the circles he runs in, this movie sets him up for future instalments though and he is pulling the strings.
Well, he's one of the people pulling the strings. As I said, this movie would hint at the 'Justice League movie' and would build on it a bit, Wonder Woman would likely be reference, make a cameo or even play a role in the sub-story. She's there to keep an eye on the new open super hero and report she likes the cut of his jib and to continue investigating stolen alien tech that was confiscated by the UN but has been ending up in specific government or business hands (Yes even Wayne Enterprises). That is the hook for the main villain of JL movie.
I'd probably want a sub plot involving Lois, Jimmy and maybe with 'Diana Prince' helping out with their investigation a bit while she also ensures Superman doesn't need help but otherwise letting him deal with problems to see how he does. (I do worry that could render any tension moot though so maybe just background references?)
Plot.
Lois, Jimmy and Clark, (possibly) a mysterious rep from the UN up on stage along with lots of other reporters, are all on hand for the reveal of Lexcorps newest invention. The world's first bipedal mech suit, large, in charge great for disasters and "defence" as it can hover, shoot, grab, smash, lift and is just plain old 'super' in pretty much everyway. (Clark grimaces)
Lex is evasive, and or BSing when talking about the power source and is eager to show off his latest toy to the public. Piloting the machine for the demonstration is none other than Mr John Corben, all American soldier, pilot, and generally great guy, but don't worry folks he's done this before and even has an AI to help him! Corben makes a scripted joke about it stealing a job he doesn't have yet, and or "stealing my job of being shot at" getting a sort of rehearsed laugh and showing he and Lex have worked together before. (He probably would get an earlier scene show he's a nice enough guy before this maybe?)
All seems to be going well until the mech starts stumbling a bit, the lights flash a different colour for a second, maybe green, and its suddenly gone off script and the cock pit view of Corben shows he can barely direct it anymore. "Diana Prince" and Corben want everyone out despite Lex being utterly convinced he can handle this, she probably helps Lois and Jimmy giving Clark a chance to jet.
Thankfully while off script the mech isn't hostile, yet, but it's not bothered about almost stepping on people and it is linking up with another mech on display. Superman sees the second one activating and doesn't wait, he smashes the inactivated mech in half then goes for the main one, intent on freeing Corben and stopping the would be rampage. He's winning until he cracks open its chest and finds a glowing green rock that saps his powers, leaving him helpless, Corben tries to help stall the machine and Diana likely does something to give Superman the edge he needs to win. However before truly off lining the mech activates its self-destruct sequence.
(Lex may lose his hair here if Mercy and or Diana can't, or won't, stop him from trying to get back in to take control of the situation.)
The mech explodes, thankfully not a huge blast due to safety protocols but the building is rubble, the machines damages and Corben is a brunt crisp that Superman flies to hospital.
Diana wants to shut the whole thing down and seal it off for the UN to investigate but Lex's money and connections are screwing that over, Lois is following her around sensing a story. Corben ends up transferred to a private practise owned by Lex and is suddenly not able to accept any visitors no matter what and security footage is disappearing. Mercy was handling this while Lex was recovering and kept Lois/Jimmy/Diana blocked from the scene much to their chagrin.
Lex, is pissed, he blames Corben for failing, Diana for taking control of the situation, Superman for blowing up his mech and generally shows himself to be a massive egotist who cannot and will not accept his own mistakes or failings. He was only able to scrounge half the tech and surveillance footage that he wanted, the rest being too damaged or taken by the Government which he is also worried about. See, the mechs were built half through his genius and half via alien tech he's been buying off the Black Market and now he's in hot water everywhere.
Deciding to blame it all on Superman he figures he can make him a scapegoat and try to get out of any public trouble by trying to make him look responsible for the mech going nuts "He has all kinds of powers, who is to say he couldn't have caused this?" But he also gets inspired seeing both the Kryptonites effect and Superman's strength, and decides to get in on all of these things at once.
Going to Corben he and Mercy convince a very delicious with pain and drugs Corben he can't be fixed normally and will die soon thanks to Superman damaging the cockpit (which was super reinforced to protect the pilot in case of self-destruction) He agrees, but they are lying and while damaged and burnt he 'could' have returned to something like normal life.
Instead though the surgeons and engineers, with Lex doing much of the work himself, begin cutting, tearing, reworking and fusing metal to his body that was salvaged or in storage. Suffice to say it's an unpleasant process. While this is going on Lois, Jimmy and (Possibly) Diana are gathering info, Superman is trying to deal with the public bouncing back and forth on him and then this nut job Mettalo shows up.
Suffice to say, being exploded, burnt, drugged, and turned into cyborg that's powered by a radioactive rock then told its all Superman's fault has not done Corben any favours. Lex wanted to frame Corben as the next, next step in warfare and peace keeping by having him defeat Superman, reveal him for a con, then kill him, though Corben is going off script due to drugs, pain and rage. (Lex is fascinated by the battle even while angry about his 'machine' disobeying him)
Suffice to say, Superman overcomes his concerns about Kryptonite and his failure with Corben that led him to doubt where he should be a hero, and wins (Likely using led) Diana, Jimmy and Lois uncover Lex's web of deceit, (Superman/Clark may have helped here as well of course) leading to Mettalo being locked away and semi-deactivated, Superman being loved by the public Lex fighting off court cases and shadowy government groups being ticked at him.
Elsewhere, in a lab at Wayne Industries, a Scientist/thief with a name tag Nigma or with a question mark themed tool is studying/stealing a metallic black box with the same lighting pattern on it as was seen on Lex's mechs, it then flashes to life. (cut to black)