Currently nothing is known about Saint Germain's origins.
He wanted to meet with Richard the Lionheart. He knew Richard was seeking out the legacy of King Arthur, so he arranged a drunken poet in the tavern to spread tales about King Arthur legacy. Saint-Germain was driving his car towards him. Although Richard's vassals were cautious towards the man. Saint-Germain calmly surrenders and he accidently blurted out his arrangement, which caused the knights to draw out their swords. When he mentions Alexander the Great, Richard orders his men to step down and allows Saint Germain to introduce himself. Saint Germain offers to assist Richard in the grand fraud of making him into a legend. He would go on to serve as Richard's court mage.
He wore gaudy nobleman's clothes whose coloring made him look more like a court jester than royalty. An odd hat was perched atop his head.
When Ayaka was dreaming about Saber's past, she sees Saint Germain offers his service to Richard. To Ayaka's surprise, Saint Germain was able to see Ayaka within Richard and he offers his service to her.
Saint Germain claims that he is not a magus, fairy, incubus, hematophage, someone traveling backwards in time, or a world-hopping Magician, saying that he is just "merely an aristocrat and a swindler." Through some unknown means, he has met both Alexander the Great and Richard the Lionheart in person. He has knowledge of Ayaka Sajyou hundreds of years in the future from Richard's time, able to correctly gauge the moment she would be viewing Richard's past through their shared dream.
He has a customized car that he is shown to utilize even in the 12th centuryWP. It is said to be decorated with "steampunk gears and gothic-looking iron barbs" described as giving it a"gaudy and twisted silhouette." Upon making his appearance, the cars' windows lower to reveal musical instrument-like contraptions that play a "twisted, cacophonous tune."