Fafnir Rann
Fafnir Rann was the captain of the First Assault Cadre of the Imperial Fists during the Battle of Phall and subsequent Siege of Terra, along with being the eventual first High Executioner of the Executioners chapter during the 3rd founding.
Youth
Fafnir was born on Inwit, and found near the River of Life. The clan of The Raan took him in, due to his real mum being dead and his adoptive one wanting a kid. As a youth, Fafnir was taught how to cook, sew (yes sew clothes) and most importantly, fight. Fafnir had been raised to believe it was his destiny to fight against House Dorn, ye, as in Rogal's grandfather. Then, in his early to mid-puberty, his fate was changed. Rogal Dorn arrived on Terra by that point, meaning Inwit changed, a lot. Fafnir was amongst the natives who joined the Imperial Fists.
Crusade and Heresy
Not much can be said of Fafnir during the crusade.
By the Battle of Phall, he had command of the battle-barge Blade of Perdition, which would eventual be seen with the Executioners during the Badab war. He had taken the rank of Lord Seneschal the presumed equivalent of a Centurion, and the captaincy of the First Assault Cadre. He survived this battle.
During the Battle of Pluto, he commanded one of the Three Sisters of Spite frigates. In the Solar War, he saved Sigismund like a total bro.
At the siege proper, he commanded the defences of the Lion Gate Port, doing an admirable job, a Dorn claimed the defence had lasted longer than he had anticipated. He battled Warsmith Kroger of the Iron Warriors. Neither killed the other, just wounding each other. He later worked alongside Sanguinius.
Personality and other notes
Fafnir is shown to be a loyal friend and warrior. When he comes to save Sigismund from Aximand. He was also shown to be a little more human than many expect of a cross between a World Eater and Imperial Fist. During his recollections of Inwit and the lieutenant-commander of the Lion's Gate, a Terran-born Fist named Haegar, he speaks of Inwit with fondness. Much to the annoyance of the other hundred Fists with him at the time, indicating he likes to run his mouth a lot. He is also shown to be a decent commander. Sallying out from the Port in a well organised counter-attack, much to the shock of the Iron Warriors. However, whilst he is a good commander and warrior, he still gets beaten by Kroeger of the Trident, though still managing to wound his opposite. However, his eventual fate after founding the Executioners is currently unknown.