There Will Come Soft Rains

Sehun/Luhan Since there are a lot of questions and confusion regarding the ending, I will clarify it here. SPOILERS AHEAD !! Sehun killed Luhan, because he (Sehun) was dying (the crack in his leg). He didn’t want Luhan to be alone when he died, (and possibly didn’t want Luhan to see him slowly die either). He was dying by slowly crumbling to dust, as it hints in the story that’s how everything, including Wu Fan, ended up.