Nohis was once a honorable space marine who fought 500 years in battle for his chapter when he was mortally wounded in a relief operation by a Tyranid. Once he was found, his body was mangled, though somehow he protected his banner until he was unable to, and due to this there was not a single tear on the banner. For this reason he was made a Venerable Dreadnought Banner Bearer. Sure he might look mighty on the outside, but inside he still is a mangled corpse in the eternal hell of suffering. Even when he is on a mission his mind still seems to keep his old traits with no nonsense goals. He still kept his comradery though he seemed to usually be quiet. He seemingly knows that his body will eventually perish and his walking coffin will be retrieved and recycled like nothing ever happened.
This only is how he became a dreadnaught and little bit about him being a dreadnaught