When did Mary Jane discover that Peter was Spider-man?
When Peter told Mary Jane originally, she revealed to him that she always knew. According to the ‘Parallel Lives’ Trade Paperback which tells the origins of both MJ and Peter, published in 1989, Mary Jane discovered Peter’s secret identity the night of Uncle Ben’s murder. Mary Jane was at her Aunt’s next door to Aunt May and Uncle Ben’s house. She had spied Peter before that day and thought of him as being rather cute (apparently she’s always had a crush on him). The night that Uncle Ben was murdered by the burglar, Aunt May was brought next door to Mary Jane’s Aunt Anna’s house. They cared for May there while Mary Jane looked out the window to see Peter learning of Uncle Ben’s death from the police. Next, she witnessed Peter go into his house and…SURPRISE!…Spider-man crawled out of Peter’s window! Mary Jane wanted to chase him down, because in the previous weeks she had become infatuated with the mystery of Spider-man. Being that she already liked Peter and had a bit of a fangirl
