What Sin Did Dan Heng Commit?

If you’re like me, obsessed with Honkai: Star Rail lore, you’ve probably asked: “What did Dan Heng do wrong?” Why is he banned from Xianzhou? Why does Blade hunt him relentlessly?

What We Actually Know

Before we guess, let’s gather what the lore gives us:

• Dan Heng is barred from Xianzhou. It’s said he committed one of the “greatest sins.” From official stories, he doesn’t remember much of his past either. 

• Blade is immortal—and he resents that immortality. Blade is a Stellaron Hunter who has lived for ages, but he sees his eternal life as a curse. He’s tormented by it. 

• Dan Heng and Blade share deep history. The lore suggests they were extremely close—trusted companions, perhaps even more than that. 

• Vidyadhara / Dragon traits and “breathing life” powers. Dan Heng is speculated to be part of the Vidyadhara race, which has draconic or other immortal traits. One beta dialogue references a “breathing life” power that can revive withered life. 

So the pieces align around immortality, resurrection, betrayal, and forbidden power. Now let’s see how the theory binds them.

The Theory: Dan Heng’s Sin Was Granting Immortality to Blade

Here’s the heart of the Reddit theory: Dan Heng used a power (or made a choice) to make Blade immortal — forever tying him to eternal life he never asked for. Because immortality is taboo in Xianzhou (or at least heavily frowned upon), this act is his “sin.” Blade views his immortality as a curse, and that resentment forms the center of his hatred.

Key Supporting Ideas

1. “Breathing life” power that revives
   One in-game beta line suggests someone has the ability to revive or restore dying life. If Dan Heng was the one who used this on Blade during a critical moment, that might be the “turning point.”

2. Artifact lore: “turn the beloved into a monstrosity”
   A description from Blade’s “Passerby’s Roaming Dragon Bracer” talks of the “beloved” being turned into a “monstrosity” and pushed into eternal hatred. The text is poetic, but many fans interpret “monstrosity” as immortal suffering. 

3. Intimate relationship hints
   The lore shows Dan Heng and Blade once shared deep bond—sparring, moon-gazing, wearing complementary artifact pieces. It suggests that the act was personal, not just cold logic. 

4. Banished from Xianzhou & memory blanks
   If Dan Heng’s action violated cosmic or social law, being banned and having his past erased or suppressed aligns with punishment. His missing memories make sense if the sin was so grave. 

Why I Think This Theory Holds Weight (and Its Flaws)

What I Like About It

• It explains Blade’s hatred deeply — not just as rivalry, but as agony from forced immortality.

• It ties Dan Heng’s banishment and identity loss** to a singular pivotal event, making the lore cleaner.

• It fits the theme of Honkai—power, consequence, and sacrifice.

What Still Doesn’t Sit Right (for Me)

• We don’t know the mechanics: how did Dan Heng gain or use such power? What was the price?

• Immortality is a dramatic move. That act might be too definitive unless later lore softens or complicates it.

• Some lore hints may be misinterpreted. Artifact descriptions are poetic, not always literal.

• The theory leans heavily on inferred, not confirmed, pieces.

If this theory is true, Dan Heng didn’t just commit a betrayal — he tried to save his beloved… with a power that damned them both. Blade’s immortality, Dan Heng’s exile, their broken bond—all of it becomes tragedy, not villainy.

I’m holding onto this theory until future story updates confirm or twist it. But for now? It’s one of the most emotionally resonant interpretations we have.