Peter Parker was the CEO of Alchemax and the former Spider-Man of 2099 more than a century ago. The Anti-aging technology has allowed him to live longer than normally expected. Guilt ridden over the loss of his loved ones from long ago, he was presumably working behind the scenes and capitalized on Walker Sloan's time gate technology and his trip into the past.
With respective realities of Miguel O'Hara and Peter Parker in flux, the Peter of 2099 planned to rewrite the reality in his image and bring all those he cared about back from the dead. He battled Miguel O'Hara using a Iron Spider suit, but was quickly incapacitated by the combined efforts of Miguel and the loose tentacles of Atrocity stuck in the timestream. Peter is eventually defeated by Miguel and is presumably returned to his orignal history when reality is restored.
This version of Peter Parker is weaker than his Earth-616 counterpart as he required an Iron Spider Exo-suit in order to be on a more level playing field to Miguel O'Hara, which he commented with "If he was confident about fighting you with his own strength and agility, he wouldn't be bringing out the heavy metal".