I really love all the different Sfawtde & dawtde AUs explaining how Derek manages to live and scrape by, living a maybe painful life with the King stuck to him, or AUs where Avery gets possessed. But hear me out on an AU where D3rlord dies, but takes the King's old place as they merge from Minecraft, to the real world. The KIY is no longer everything that exists, because now it is Derek who permeates every force and will in the universe.
Imagine, the malevolence of such a sentinel being replaced by the level-headed curiosity that Derek has always had. He would be a much kinder entity that absorbs the world. (And it would be sorta funny if this "concept of everything" is called Derek)
And even being such a Lord of vast and infinite experiences, D3r will go back to look for Avery. He knows where Avery is, of course, but Derek looks out for him, makes it so that they are always on time for appointments. Makes it so that Avery finds loved ones who soothe his grief and that he is happy with life, doesn't blame the world anymore. Makes the leaves of the trees in their neighbourhood more green and more red, and tells Avery, that yes. Derek cares.
Well Avery may or may not have known how much human Derek cared, but D3rlord will spin his knowledge in every way he can to show Avery that the world is full of his adoration for them.