This is AU season 2 for Heroes and AU season 7 for Smallville. When Peter exploded, he killed Nathan. Wracked with guilt, he decides he can't go back to New York. Everyone else in the cast goes back to their lives as best they can. On the Smallville side of things, Chloe survives her near-death experience of healing Lois, Clark saves Lex's life and defeats Bizarro. Kara hasn't come to Earth yet. Lois moves to Midway City to get a better reporting job. Also, Peter is younger, only about two years older than Chloe. That's basically all you need to know.
Peter was walking. He had been for several months, never staying too long in one city. He didn't want his mother to find him. She would only bring him home, tell him that Nathan's death wasn't his fault. He didn't want to hear that and he couldn't go back to New York. His life there was over. Without Nathan, he had no idea what to do. Metropolis was his latest destination. He spent a few years there as a kid and kept in touch with one of his classmates, Chloe Sullivan, through e-mail. From Chloe's last e-mail he found out that she worked at the Daily Planet. He planned to visit her at work for a while and then get out as soon as possible. She always made him laugh and he couldn't allow himself to feel happy for too long. He didn't deserve it. But he desperately wanted to see someone who could remind him of better times, if only for a short while.
Chloe's world was almost unrecognizable from what it was just a few short months ago. Her best friend was dead. Her cousin was gone, moved to another city. She and Jimmy had a falling out and he moved to Star City to take a photography job. And to top it all off, Clark, the one person she thought she could count on to be there for her had completely thrown himself into his superheroics and barely spoke to her. She was truly alone now. Sometimes she wished she could have just stayed in Metropolis and never moved to Smallville. Life was better there. She didn't have people with telekinesis or some power trying to kill her on a weekly basis. She was just a kid. How she missed those days.
Lex was a broken man. Lana, the woman he loved more than anything in the world was gone forever. His life had been saved, but everyday he wished he would have died. Anything would have been better than the guilt he felt for deceiving her about her pregnancy. All he had left were his Luthorcorp projects. A few days ago, a team of his acquired the corpse of some sort of super-being from New York. He was determined to revive this man and discover how he gained all of the abilities he supposedly had. Abilities he would take for himself.