Here it is. Theories are italicized During the Great Disaster on the Moon, many horrible things happened. Wei Ning was killed, the Necrochasm was forged, and Dredgen Yor turned to the Dark. With the help of Hive magics, he turned his Rose into a dark Thorn. He used it to wreak terror across the system, killing civilians and Guardians alike, including Thalor, Pahanin Errata, [i]and three humans known as Brevin, Trenn, and Mel[/i]. Jaren Ward was a Hunter who wielded an old, Tex Mechanica Hand Cannon he called the Last Word. He arrived in a small town called Palamon, claiming to be passing through. He met a young boy known as Shin Malphur, who was entranced with his cannon. After staying for many months in Palamon, Jaren attracted the hate of the dictator, Magistrate Loken. In a 1v10 duel, Jaren put a bullet between Loken's eyes and stared the other nine down. [i]Eventually, Dredgen Yor would raze the town for unknown reasons[/i]. Jaren took Palamon's survivors on a hunt for Yor, tracking him across the wilderness. [i]During the hunt, three of Jaren's "kids" attempted to apprehend Yor, but were gunned down[/i]. The chase continued. One night, Jaren went off on his own to confront Yor, leaving Shin and the rest of the team in the camp. Shin heard multiple shots going off, belonging to Jaren's gun. Then one shot, dark and infernal. Then silence. Eventually, everyone left except Shin. Jaren's Ghost found Shin, and bathed him in the Light, turning him into a renegade Guardian. Shin took up the Last Word and continued the Hunt. On Mars, for reasons unknown, Dredgen Yor finally said goodbye to his Ghost. It is possible he was there for the Crucible, where he ended Pahanin's Light. [i]Yor's Ghost eventually happened upon Holborn's Host, who were looking for the Warmind of Mars[/i]. Eventually, Shin and Dredgen faced off on Dwindler's Ridge. Repeating Jaren's iconic words "Yours. Not mine," Shin killed Dredgen and avenged the death of his teacher, his third father, and his closest friend, Jaren Ward. [b]The End[/b]

Amazing! There are 3 flaws I see (that I interpret it as. First, I don't believe Dredgen chose to make Rose into Thorn. It is a Weapon of Sorrow, just like Necro. He just got screwed when he found it again, this time as Thorn. Second, and I know you said this was a guess, I doubt that he was there for crucible. Everyone already knew he was a murderer at this point (killed the Crucible titan and Pahanin). Lastly, was it [i]his[/i] ghost that stumbled upon the team on Mars? I thought it was the ghost that came to Mars looking for a guardian but never did, and so he discovered Cabal Intel for the Tower, etc.

After Yor was corrupted, he saw his Rose as different. And so he changed it to match his new views of it. We don't have an exact timeline of his murders, so we don't exactly know when he murdered Pahanin. The Super Good Advice is on Mars, so... That part is a theory. The Ghost who went looking for a Guardian on Mars is not Yor's, but the one encountered by Holborn's Host may be