The unnamed Master of Archer is a rich businessman who lives in a penthouse inside his skyscraper office building. He holds an interest in getting the Holy Grail and will do whatever it takes to get it.
During the 1991 Holy Grail War, he secretly supported Nigel Sayward who was the Master of Lancer and made a deal with him in exchange for information regarding the Holy Grail War. After the First Holy Grail War ended, he later decided to participate in it himself.
The unnamed Master of Archer is a tall young man who has short dark brown hair and grey eyes. He normally wears glasses and his Master's Degree is located beneath his left eye.
Not much is known about the unnamed Master of Archer's personality.
However, in Fate/Prototype: Fragments of Sky Silver, it is revealed that he is a smart intelligent man who "sits in his skyscraper like a ruler." He is filthy rich - so much so that he calls buying classical cars as "chump change," and owns several luxury high class cars including the company ones.
He also doesn't think much of magi lineages or blood ties. But, he can also be driven when he wants something and views the Holy Grail War like another business deal. He is also capable of keeping any deal that he makes, even if it includes disposing corpses.
Fate/Prototype: Fragments of Sky Silver Edit
In Fate/Prototype: Fragments of Sky Silver, the unnamed Master of Archer appears in the very last chapter "Fate." He is not a Master at this point of time in 1991, but it is hinted that he had made an attempt to do something during the first war through an unknown party and was starting to make preparations to participate in the second.
He is first seen bumping into Tamaki Kitano at the JR Tokyo Station, coming back from a trip. After Tamaki apologizes and notes his appearance, Archer's future master says "Excuse me" and walks off.
Outside the station, Archer's future Master is greeted by his driver and gets into one of his privately owned German made luxury cars. Getting into the car, he tells his driver to go to West Shinjuku. After a brief lighthearted conversation with his driver, he then places a phone call to an unknown party. Connecting, he greets the unknown party and asks if he/she screwed up in the Holy Grail War. He then offers the other party a second chance and tells them to retrieve a relic for him, preferably one from the most powerful Heroic Spirit.
As he looks out at the urban buildings past the Shuto Expressway, he continues the conversation by mentioning Nigel Sayward. In the part of his conversation about Nigel, Archer's future master states that he had bought information about the Holy Grail War from Nigel and that he has preserved and digitized it. He further admits that Nigel had taught many things prior to his death and that Nigel's price was that Archer's future master would dispose of his corpse if he'd died.
After stating his opinions on magi lineages, Archer's future master declares that he won't let the Holy Grail escape next time.
In Fate/Prototype, this master succeeds in summoning the most powerful Servant when he summons Gilgamesh.