This is an article that I suddenly became interested in. Parallel World Shirou Emiya, referring to the setting of Senki's Zeske, (Chrissy was replaced, not intentionally, and was rescued by default and lived an ordinary life, but Shirou would not just copy Chrissy's original lines and character)
Principle: Babylonian treasure house gate (Shirou's old design, the source of "Emiya"), red archers, tsundere, so Emiya Shirou = Yukine Kris (bushi), personal interest, the protagonist's old sword (appeared late), the rest are Artoria and its subspecies
Purpose: Old Swordsman