Concept Breakdown

So i have a general idea of what i would like the sons of lunacy to be and have begun scribbling, yes scribbling, some notes down. So far i have decided that they will be one of the two lost chapters, specifically the XI chapter created from the gene seed of the god emperor(may he die a horrible death at the hands of Abbadon). The Primarch will be called Lucius Demacles and was found on the planet Themis, a developed world that will be based off of medieval Europe's knight system and look but still developed enough to have bolters and such. This will shape the general look of the chapter. The armor will be ornate and (with the help of alot of green stuff) heavily modified. I still haven't picked out colors yet but i am playing around with the space marine painter on bolterandchainsword.com. I might post some of the concepts i come up with. They will just be a general idea of what the colors will look like as i will be modifying the helms of the marines to a more medieval look and probably so some other work with the pauldrons and backpack. Ive also started the nerdy work of creating the origin story of Lucius and his pre-heresy chapter that will for the time be called the Heralds of the Imperium. If anyone actually reads this any ideas would be helpful.