"...His Glory brings salvation to those who embrace his ideals. Even the fallen are offered a chance at redemption in The Emperor's service.
Death. Sacrifice. Duty. Honor.
These are what the Emperor requires of us." - Lord Admiral Spire, final words and testimony.

"once the noble defenders of humanity...now its most vile offenders"
- Chaos Space Marine Manuel

The Chaos Space Marine's voice had reverted from deep and gravelling to the voice he once had prior to his fall to Chaos.

“Forgive me… and… forget me “

That hit harder than a power fist.

“Do unto me as you did to Lupercal. Erase my very soul so I can be beyond this pain of memory.”

The fact that he doesn't wish for redemption is very powerful. He knows fully well his sins. But after the hazy cloud of Chaos left his eyes he felt all of them, weighing on him more than his armor or weapons ever did.

He wants The Emperor to erase him, and all trace of him.

"I am weak, because the power that was given unto me has never been mine."

When Angron turned into a Demonprimarch after Nuceria, he had 2 Moods.
1. Breaking every seal, cell and chain that held him and killing everything in his lair on the conqueror.
2. Crying in a Corner and begging the Emperor for forgiveness and to save save him.

For a Chaos Space Marine to regain his sanity is a true feat of spiritual strength

It gave him power but robbed him of his own self and character.

I came for the art and left a bit of m'y soul in the process. I wasnt suppose to cry... But i did

"I won't beg for forgiveness. I don't want it, I don't deserve it. Whatever is coming for me after I die, I embrace as inevitable and just"

Reminds me of the death guard marine who realized how disgusting and inhumane he and his brothers had become

The Emperor stood before him, calm, yet wrathful. Eyes that were both youthful innocence, yet elderly knowledge. He stood there, staring down at the Chaos Marine, "You made your choice. You will reap the consequences. No, you mustn't be forgotten, and you mustn't ever be forgiven. You will be remembered, you will be hated. So others do not fall in your footsteps. That is, in itself, your only solice. Is knowing that your death will keep unknown billions from taking the same route. And in this, I say thank you. For showing the way."

This reminds me of that story of the Deathguard marines who had their connection to the Warp severed and in their final moments they had become disgusted at what they had become and they died a painful death cause the warp was the only thing keeping them alive. Love stories like this

It goes by a different saying but it's a lesson that stays true even to this day.

There is no such thing as a free lunch.

It would hurt is the emperor was simply disgusted with him, but the fact the emperor looks upon him and is not only disgusted, but disappointed, hurts all the more for him.
He forsook the emperor for his own selfish desires and is now so much less then he ever was before.

The emperor doesn't even look mad or disappointed. He's just sad

"Hey astartes? Have you killed a traitor?"
"Long ago I've killed many during the horus heresy, there was one I couldn't kill
We were even power
After the horus heresy I found out he was one of the world eaters that betrayed the emperor....so many times I've encountered him yet we couldn't even make a kill apart of many injuries and organ failure
So many millennium has passed, he was different...no longer the brother I knew
One day we fought, this time losing my leg in the battle I managed a fatal kill on him."
"Did he cursed you?"
"No...he just smiled despite his mutation, even saw tears in his eye's looking at me
He even thanked me for killing him."
"What happened next?"
"He just looked to the skies, started saying my emperor forgive me...then one last breath he was at peace that someone ended his tormented curse"

"Hey... When do you think a person dies? When a bullet from a pistol pierces his heart? No... When he's attacked by an incurable disease? No... When he eats a deadly poisonous mushroom soup? No! A man dies when people forget him!" - Dr. Hiriluk