Complex sentence: He spends the night doing paperwork and drinking with Stryver, who boasts about being the more successful of the two; in reality, it is Carton who is the brain, while Stryver merely lives off Carton's labor and craft.
Split into simpler sentences: He spends the night doing paperwork and drinking with Stryver. Stryver boasts about being the more successful of the two, but in reality it is Carton who is the brain behind him, while Stryver merely lives off Carton's labor and craft.