"JD" was a member of the rebel forces fighting the government in the Eastern Slav Republic. He was a close personal friend of Buddy. His real name is not known, as he tells Leon that "JD" is not his real name.
JD grew up in the Eastern Slav Republic with his good friends Buddy and Irina. Little is known about JD up until the events of the civil war or during most of them, but he joined the resistance group around the same time as Buddy, following his friend into their fight for independence. Resident Evil Wikia