Edward Markham operates a shop called Markham's Used Books, which specializes in rare and collectable books. He is a long time acquaintance of Peter Bishop.
He first appeared in ("Ability") in which he was able to locate a copy of the ZFT manuscript.
He appeared again in ("Jacksonville") when he helps locate the buyer of the books that were sold to him years earlier by peter,the books actully contained critical information related to Robert Bishop, Walter Bishop 's dad and are treasured by him.
Later, he provides Peter and Bolivia (disguising as our Olivia) with a copy of The First People by Seamus Wiles ("6955 kHz")
In the alternate timeline, Peter and Olivia return to ask him about a certain symbol though he has no idea who they are. He tells them about the symbol and David Robert Jones 's apparent goals for the guided mutation of humanity. ("Nothing As It Seems")
In 2036, he lives alone in an apartment with an ambered Olivia Dunham. He pines for her and plans to wake her up eventually, but Walter, Peter, Astrid, and Etta show up to rescue her before. He appears to have become even crazier in the future trying to keep his rights and staying away from Loyalists and Observers alike. ("Transilience Thought Unifier Model-11")