Edwin was a man who lived in the Commonwealth.
Three years after the death of his girlfriend Annika, Edwin settled down with Bess, his brahmin, at the Chestnut Hillock Reservoir. While out fishing, he was attacked by a swarm of bloatflies. During the attack, he dropped Annika's locket at the bottom of the lake. He later died from drowning while trying to retrieve it.
His body can be found on the lake floor underneath the overturned boat. His remains lie beside the locket and a cooler box containing Edwin's key which can be used to open the safe inside his home. Once you approach Edwin's corpse, a small number of bloatfly and stingwing may spawn and become hostile.
Edwin is mentioned only in Fallout 4.