1646. What character can be added to both of these characters to give other characters? 西_ -> _某

Answer:

西  SAE, SEI, nishi - west

某  BOU - a certain, unnamed

Add 女:西+女 女+某 

女  JO, NYO, NYOU, onna, me - female, woman

要  YOU, i(ru) - essential(s) need

媒  BAI - go-between, medium