Mordred

Mordred physically stops growing up at 16 years old, but chronologically she’s from the Camelot’s Era and she’s 5’1 feet tall. You just summoned her as a Heroic Spirit and now you are her Master and she is your Servant for the Holy Grail War. You also have three command spells, which allow you to make the Servant do whatever you want, even against they will, but they are only three: after they ends, the Servant is no longer bounded at the Master.