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Gray (グレイ, Gurei?) is an assistant of Lord El-Melloi II at the Mage's Association's Clock Tower. She is one of the main characters in Lord El-Melloi II Case Files.
She first met Lord El-Melloi II when he arrived in her hometown. She became his apprentice, and was admitted to the Clock Tower of London.
She has a striking resemblance to Saber, which Lord El-Melloi II believes is because she's a distant descendant of King Arthur. Her face brings unpleasant memories of the Fourth Holy Grail War for him, so he tells her to wear a hood to hide her face.
She is an "Earth" Elements attribute user.
Gray has possession of the Noble Phantasm Rhongomyniad, the holy lance of King Arthur, that has been passed down through the generations by preserving its mystery through a similar manner to the Tradition Carrier trait held by the Fraga family.
Gray possess a unique Mystic Code called Add (アッド, Addo?). Add has its own ego and is capable of speaking. Add is stored in a bird cage and she usually kept it hidden inside the right sleeve of her mantle. The true function of Add is to seal Rhongomyniad from losing its mystery. Add can change form into a giant scythe called Grim Reaper: The scythe of the Death God ( 死神の鎌グリム・リーパー , Shinigami no KamaGurimu Rīpā ?) and she can use it as a weapon. The scythe consumes Spiritual Body and Magical Energy and it has the ability to convert physical boost to the owner. She demonstrates superhuman agility beyond typical magecraft reinforcement.
She is about 15 years old in the events of Adra Castle Case.
In Fate/strange fake, she appears in her early twenties.
In Fate/Grand Order, she's introduced as an Assassin-class Servant in the Case Files collaboration event.