AU where Alphonse never went with Edward after Conqueror of Shamballa.
He had these dreams sometimes. Dreams of another past so similar to his but yet so different. The other him had everything he could ever ask for. His brother got his body back, his father returned, he got to marry his own Winry, he had people he trusted around him. He was happy. He never had to kill his mother, he never had to come to the conclusion that someone else was walking around with his limbs, he never had come close to sacrificing people for his goals. That Edward Elric, living his best life in Amestris, was different. And this Edward Elric, stuck in Germany, was envious of him.
Jealousy, what a horrible emotion it was. It ate him from the inside, burning his core being, destroying him. He hated that he would never get to experience the same things with the other him, he despised that he was never going to be truly happy while stuck in this world. He felt no better than Envy, the monster who despised him for being his younger half-brother, despite the fact that Hohenheim had abandoned both of them.
He came to dread going to sleep, afraid of whatever happy moment that he will never get to live he would see this time. Sleep deprivation was eating him away, the dark circles under his eyes visible from miles away. He wanted to go home, he wanted to see his family again. At this point he was desperate, anyone would do, even his father.
He hated this world, he hated himself, he hated how these stupid dreams were able to influence him this much. But most of all he hated the other him, the Edward Elric that got to keep everything, the Edward Elric that wasn't killed because of who his father was, the Edward Elric who got to be happy. He also wanted to be happy. Equivalent Exchange, right? Had he not suffered enough to make up for his mistakes?
Maybe Dante was right, maybe equivalent exchange actually wasn't real. He really believed in it. For him, it used to be the one truth of the world. 'Without sacrificing something, humans cannot gain anything.' his father's books always told him, his teacher always told him. He had blinded himself with that, accepting it as the law everything in the universe obeyed. But he was wrong, like always. Ever since the beginning he was wrong. He was wrong to want to bring his mother back, he was wrong to not recognize the signs of Tucker's insanity, he was wrong to meddle Hughes into his business, he was wrong to not keep his promise that they would get their bodies back together to Alphonse. He was guilty of the Liore riots, he was guilty of not stopping Archer and the troops sooner before being turned into a Philosopher's Stone.
Edward Elric was drowning and his regrets were the rocks tied to his body, weighing him down and pulling him deeper into this cycle of self-loath and hatred.
His roommate and friend was worried for him, but his mere presence was hurting Edward even more. His name Alfons Heidrich, his face identical to the one of his brother, his personality kind and brotherly-like, the even air around him seemed the same with that of his own Alphonse. But Alfons didn't sound like him, he didn't believe in alchemy, he wasn't his younger brother, he just looked like him. And just like his little brother, Alfons Heidrich's blood was coating Edward's hands, him being gone was his fault.
Some nights Edward struggled with his identity. He didn't exist in this world, he wasn't supposed to be here. He had no papers, no passport, no documents, no nothing. Edward Elric was never a person here, he was a ghost, an outsider. He wanted this to be a dream, he was scared he wanted to be the man in his dreams, but waking up was a painful reminder of everything he had lost. He would never see his Alphonse again, he would never see his Mustang and his team again, he would never see his Winry again.
But every night he battled his own internal sins. Envy, the jealousy he felt while watching his joyful other self. Wrath, the anger he felt towards himself for not being a better person. Greed, the avarice he felt when he wished he was the other Edward, and that this was simply a dream he was having. Lust, the desire for Winry, from whom he was torn away from. Gluttony, the hunger he felt for a return to his own world. Sloth, the apathy he felt towards this world and its people, they would never be good enough for him. Pride, the arrogance he felt, and because of that arrogance he would never be able to let go of something he never had.
And now at the age of 100, Edward Elric still hadn't given up. He would never say goodbye to his Lost Heaven, to the dream of returning home and living happily ever after with everyone he loved.