Formerly gambitfairy

(LEAK) Imbibitor Lunae Dan Heng's Light Cone, "Light Brighter than the Sun" says this:

“All he had seen since his birth was this lightless dungeon. Irrelevant sins bound him to this place, and irrelevant memories engulfed him.

He struggled, doing all he could to breathe, trying to grasp a sliver of light in this fathomless ocean. And yet, when the general entered this lightless prison, he saw the gaze of a young man shining brighter than sunlight.”

Now, it's as clear as day that Jing Yuan is responsible for letting Dan Heng leave the Luofu (albeit being exiled forever for his previous incarnation's crimes), and the Light Cone depicts the moment when Jing Yuan decided to let him go.

It is implied that Jing Yuan is much younger than the others of the High Cloud Quintet, of which Imbibitor Lunae, Jingliu and Blade were a part (idk i'm forgetting the other one's name sorry). We can rule out Jingliu and Blade being the one referred to in the Light Cone's lore.

So, to sum this part up: Jing Yuan was the one who brought Dan Heng out in the light.

In the scene above, you can see how Dan Heng's side is green, gloomy and overcast, while Jing Yuan's side is bright.

He has once again brought light to Dan Heng. This time with the prospect of detaching him from the dark past he tries to flee so desperately, by saying that he won't have to walk in anyone's shadow anymore.