Background Information Edit
Christopher was abducted as a child by The Candy Man when he was younger. His "youth" was medically depleted, causing a multitude of side-effects including profound blindness.
Original Timeline (Season 3) Edit
Christopher has been trying to recover from the biological aftermath of his abduction and the dim memories of the terrifying event. His father, Colonel Broyles urges him to forget it. Diane Broyles agrees to allow Olivia Dunham on the case, believing she is their universe's Olivia Dunham, remembering her before as smart and likeable. Our Olivia Dunham tries to convince Colonel Broyles to allow her to help Christopher recollect the trauma. Broyles disagrees, but Diane believes it is the right thing to do, in order to help the current abducted child.
Olivia easily connects with Christopher due to her shared connection of childhood trauma from abuse and experimentation. Christopher begins to recollect memories, being of sufficient help to Olivia and successfully retrieving the abducted child, Max Clayton from the abuser, Wyatt Toomy. Reverend Marcus attempted to abduct Chris in his home once the conspiracy was exposed.
Alternate Timeline (Season 4) Edit
David Robert Jones is providing Colonel Broyles with a serum that reduces Chris' symptoms and heals him. As a result, Christopher is thriving socially. His father is later arrested and imprisoned for his co-operation with Jones, so it is likely he went back to his previous state of blindness.