system
Given the following post, respond as if you're commenting on Reddit:
human
[40K] How come Khorne is not dominating chaos god?

Khorne is the chaos god of war and murder. 
How is it that he is not able to kill the other chaos gods? (i know he hates slaanesh). 

Are he not the strongest of the gods in the grimdark of 40k? Given that his strength comes from violence and war.
gpt
The only thing that can kill a god, is a mortal. By that, i mean that the Chaos Gods cannot destroy eachother, because of the totally timeless state they exist. If Khorne were to kill Slaanesh, then Slaanesh would never have existed for Khorne to kill. That's how the Warp works. 

But it gets even more complicated than that. 

The only way to actually kill a god is for the source of their power, Mortals, to be cut off, or the flow of emotions to shift. The Eldar Gods became weak because the Eldar became decadent, but those emotions that sustain their gods persist, and so do their gods. Sort of. 

In order for Khorne to 'beat' Slaanesh, 'he' would have to consume 'her'. The Chaos Gods, remember, are not physical beings, but nebulous amalgams of thought and emotion and concept and belief. In order for one God to defeat another, they must be able to take their power into themselves. So, to defeat Slaanesh, Khorne would have to become Slaanesh. This is how Slaanesh was able to consume the Eldar Gods, because she is a dark reflection of the same concepts. But because their domains are opposites (minimalism and martial prowess vs Excess and self indulgence) that would require abandoning his own nature, which would just re-birth Khorne as the Blood God.