Boulder is a member of the Knights.
Boulder is the codename of Jasper Lee Jackson. Jackson was born in the Blue Ridge Mountains to a mining family. They were "forever" miners, as his father told it, coming from a long heritage that had worked in the earliest gold and silver mines in Colonial America, and on back in Switzerland and Germany into ancient times. Jasper grew up inside West Virginian mines, spent his teens in the Blue Ridge, and later worked most of the Appalachian Mountains.
Whether due to longtime mercury exposure, coal ash, and generations of deadly black lung disease, or some natural mutation, Jasper was born deformed. A giant of a hunchback, he is made for stooping and carrying massive loads through tight mines. However, there is something much more unique about Jasper. He has great affinity with rock and can gather rock and rubble around himself in a protective layer like a "turtle shell." Why rock can adhere to him is unknown, but it offers him immense durability and a form of natural armor.
Boulder is a loner and doesn't like people, partially because of his looks and the fun made of him as a child. He likes to live and work in the mountains and his coworkers always nicknamed him "The Mountain Man." However, when he was recruited into the Knights by Supreme Commander and Tom Rush, he was codenamed Boulder, due to his ability to coat himself in rock and for him unique way of tucking and rolling when fighting and fleeing. For the past four years he has lived in Queen City and enjoyed life with his new-found family of superhero friends.
Due to his upbringing and life inside mines, Boulder is very superstitious and not a fan of magic. He hated the results of Darke Day, the demons and subsequent battle in Hell, and there was no way in Hell he was staying in Hell. So he was one of the Knights chosen to return and help help defend Earth. Boulder has been very depressed about losing half of his friends in Hell.