I'd like to present the Paladins of Dorn, a Chapter in the proud heritage of the Imperial Fists Legion. They are the guardians of the Camael Marches, a wide expanse in space on the eastern fringe of the galaxy.
Historically, the Chapter originated from a Black Templar Crusade that was sent to these far reaches of the galaxy. They have inherited the Imperial Faith from their parent chapter and are allied to the Forces of the Ecclesiarchy in the Marches. However, they somewhat lack the religious fury that distinguishes the Black Templars - the split with the Templars appeared when the Camael Crusade adopted a more chivalrous code of honour, which their leaders and Chaplains perceived to be closer to the original ideals of the 7th Legion (which has been rejected as erroneously by both the Black Templars and many imperial scholars since then), as well as the use of Librarian psykers and a pragmatic attendance to the tenets of the Codex Astartes.
Since then the Paladins of Dorn have developed their own philosophy of knighthood. While they have reliably protected the Camael Marches and slain many foul Xenos and Heretics, their rivalry to their parent chapter has, unfortunately, not always stayed non-violent over the centuries.
In the era of the Dark Imperium, the Paladins have grudgingly accepted Primaris Space Marine reinforcements, which are still distrusted by many in the chapter.