Here´re some ideas that I´ve been putthing together for a while.
SUPERMAN: THE LEGACY
ACT 1- Superman is at the top of the world. He can protect/save people from anything, from working accidents to terrorist attacks, he´s beloved by all, Lois is more and more crazy about him, even though she still doesn´t know he and Clark are the same person, sill teases Clark and everything.
But then Metallo surfaces and suddenly attacks him, with Luthor, more spiteful than ever of Superman´s success, pulling the strings. A big fight ensues, at one point Metallo seriously weakens Superman with Kryptonite and throws a ton of tocks and concrete on top of him. As Superman struggles to release himself, Metallo wants to sadistically demonstrate his fragility and kills an innocent person in front of Superman. Enraged, Supes manages to release himself and defeat him. People still cheer for him, but the death haunts him.
With Ma and Pa Kent, as Clark, he ponders, what if I let the people of Earth down, what if something terrible happens that I can´t stop, even with all my powers and popularity it can all go away in a blink. They reassure him, with all his powers deep down he´s as human as any of us, and that´s his real greatest strength. He flies away feeling better, wathing the beautiful fields of Smallville. As all of these happens, the hordes of Darkseid conquer another world with the iron fist of his army, and get closer and closer to Earth
ACT 2 – Darkseid´s army attacks Earth with all its power, causing huge devastation. Superman fights his army with all his might, but even he can´t contain such power. Luthor makes a deal with Darkseid to help him as the new ruler of Earth.
Dr. Hamilton clues Supes that he´s found the location to Apokolips, maybe with the ship that brought him to Earth he can get there, take advantage that Darkseid and his main army are absent, and find something that can help save Earth. He alerts him, though, that the distance from Earth´s yellow sun will seriously weaken him. Superman is afraid, he couldn´t save Earth with his power, can he do it without it. Pa Kent reminds him that bad things happen to anyone, but you don´t need super powers to overcome these bad things or even impossible obstacles, but strength of mind and heart.
Superman kisses Lois goodbye, thinks for a moment that he may never see her again, and reveals his true identity.
Superman is forced to leave Earth at the blink of obliteration, just as he once had to leave Krypton.
On Apokolips, Superman finds an entirely different situation from Earth. His powers are seriously reduced, the mere mention of the name Superman inspires hatred and rage, he has to be as undercover as possible. In disguise, he uses his skills as an investigative reporter to infiltrate Darkseid´s palace.
In there, however, he´s uncovered and Kalibak decides to destroy him. They fight, and even weakened Superman manages to figure out his weakness and defeat him.
Because he´s Superman and he can see the humanity in even the worst of creatures, he sees Kalibak for who he is underneath: a frustrated son, desperately seeking a father´s approval that will just never come. Superman understands him, he has to live up to the legacy of two great men, the Kryptonian scientist and the Kansas farmer, to an entire race that has him as its sole survivor and a planet that adopted him. He manages to reach out to Kalibak, who reveals him a secret that will help save Earth from Darkseid (I´m not sure what that secret is yet, let´s save some surprises for my meeting with WB, hehe…

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As all of this happens, Earth falls more and more under Darkseid´s tyranny. Luthor realizes some of his deal with him isn´t being fulfilled and, angry, goes to Darkseid only to find out he´s been double-crossed for Darkseid to get access to his advanced weaponry technology, and is thrown into the dungeons with the rest of the slaves.
ACT 3 – Superman returns to Earth and finds the planet under dictatorship, people enslaved and caged by Darkseid´s reign of terror. More determined than ever, Superman fights with all he´s got and finds the key to get Darkseid to leave the planet, thanks to the secret Kalibak told him.
Darkseid accepts his (momentary) defeat and prepares to leave, but before he reveals, Lois resisted bravely all the mental and physical torture, which was tremendous, but in the end she had to give in. I know your secret, Earth´s champion, and will use it to my advantage. He didn´t kill her though, because Superman´ll be so busy and tortured helping her to recover from all the trauma, and being reminded of his mistake, it will weaken his spirit even more.
But Darkseid also knows where he gets his guidance and support from, and that won´t be there anymore for him.
And then he obliterates Smallville from the face of the Earth with a hidden nuke.
Blind with rage, Superman attacks Darkseid but he manages to escape.
Luthor is prosecuted as a traitor of the human race, and awaits for lethal injection.
Clark and Lois, still in a wheelchair, attend to a collective, symbolic funeral for the people of Smallville. Nobody but Lois and Clark understand why he destroyed a city with no strategic importance of any kind. With tremendous sadness, but more determination than ever, he remembers they tought him their last but most important lesson: deep down he´s as human as anyone else and bad things still happen to him, to Earth and to those he loves. But that humanity is his greatest power, for it gives him the strength of mind and heart to overcome tragedy and surpass impossible obstacles. This isn´t the last we saw of Darkseid, and he´ll pay for this and for all evil he´s done, he oaths at the memorial for his adoptive parents and the people of Smallville. It isn´t truth that you won´t have guidance and support, says Lois. I´ll be here for that, too, as she holds his arm.
After the funeral, Clark gets a call from Dr.Hamilton, he may have something important for him to know, regarding Darkseid. Clark kisses Lois as the wind blows autumn leaves around them. Discretely, he hides and changes suit. Superman takes flight, watching thebeautiful mountains and forests and the sun rise, as he disappears in the horizon.