It's Mortallian (Foreshadowing Payoff)

Mortarion had never been this calm.

In an instant, he recalled his entire life: falling from his infant capsule onto Barbarus, rising to power, returning to the human world, beginning the Great Crusade, and following Horus into rebellion.

His face was blank, his expression dazed. He looked even more miserable than when he had just been steeped in Nurgle's virulent poison.

This peculiar sensation of touch...

It was unfamiliar, yet carried a hint of familiarity.

Still unwilling to accept it, he grabbed at it a few more times. In the end, his heart died.

With the Primarchs' innate knowledge, he clearly understood this organ's physiological properties, its particular anatomical value, and its vital significance to human reproduction. But this was absolutely not something a man should have.

He could even feel that his armor had become somewhat constricting, no longer able to perfectly accommodate a Primarch's body.

In the past, Mortarion would only have felt that his body was becoming tougher and stronger. He would have joyfully shared that delight with his sons.

But now, Mortarion's soul had gone numb from the inside out.

The Primarch knew perfectly well what had appeared on his body.

They were biological organs used to nourish offspring.

Compared to the Aeldari goddess of life before him, Isha, Mortarion was no less endowed.

What the fuck was this?!

He didn't want this! He didn't want this, damn it!

Yet what terrified Mortarion even more was that it was not merely his chest that had changed. His neat, practical short hair was growing at a visible speed.

It reached his shoulders, then his waist, and only stopped when it reached his hips.

It was a head of flowing pale-green hair, gradually drifting in the breeze of the Garden of Decay.

And beyond his sight, Mortarion's buttocks