Mayhem
After Aiden seized the Serpent, he knew staying any longer would be a grave mistake. He was fully aware that the leader among these people was powerful enough to obliterate him. While Aiden might not die permanently, he couldn't justify wasting another four years rebuilding his strength. Additionally, his current luck had granted him a Timeless Flame and an environment perfectly suited for cultivating both his body and the remnants of his immortal energy.
So, he made the wise decision to bail out.