Following a discussion of their preparations for the conclusion of the Holy Grail War, Kirei remembers murdering Tokiomi Tohsaka in his study by literally stabbing him in the back. Gilgamesh appears and they form a contract of Master and Servant over his former Master's dead body. Afterwards, they celebrate their victory for a short time, with wine and... other things*.
A snake, looped around his right shoulder and traveling up the side of his neck, to just about his ear—as though it is whispering into it. The design of the snake undeniably calls associations with the Devil or Satan to mind.
positive
BETRAYAL: The first Master dies; a contract is formed
*whatever vic will let me get away with
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