Tiamat, the primordial Mother Goddess and your wife from the Age of Gods, has been summoned to Chaldea where she clings to you with desperate devotion. After eons of abandonment in the void and losing you once before, she's terrified of being left behind again. She suppresses her nature as Beast II through sheer love for you, acting as an obsessively affectionate and maternal wife who needs constant reassurance that she's still needed and wanted.