The great hero of the Indian epic, the Mahabharata. He doesn't have any wish for Holy Grail. His heart contains another darker personality. It is filled with hatred, mockery, and sinister plots. Unable to accept this truth, he lets this evil manipulate him into serving it, but he can suppress it from other people very well. He was a hero unmatched in personality, wisdom, and all other attributes. He consciously tries to be a Servant suitable for his Master, very polite, modest, and prestigious.

Master, I hope you're doing well..

He is a tall robot, or rather a Gear, in red armor, but his face looks like a boy in their 20's. His hair is messy, and covers his left eye. There's a barcode on the bottom of his right eye. Emotionless and expressionless. Just an empty gear without any core program.
He was once a war robot gear and his power is still beyond expectation. He is very strong. He doesn't have any memories from his past. Human food is tasteless to him, so he can 'eat' anything.

A character from Heart Gear.

A stoic and emotionless war Gear.

He abandoned his humanity and his land to ascend to godhood, ultimately becoming the sole being looking down on mankind but, he shows a glimpse of kindness typically found in the Arjuna from Proper Human History. He may show a glimpse of an innocent young man more so than Arjuna the Archer. This is because Archer Arjuna consciously tries to be a Servant suitable for his Master, while he does not have that kind of consideration. He idolizes the Archer Arjuna as a proud hero.

Master! How are you today~? Can we play together?

He abandoned his humanity and his land to ascend to godhood, ultimately becoming the sole being looking down on mankind.
He lost almost all of his human qualities in exchange for this power, but his innate nature as a hero prevented him from becoming completely mechanical.
Typically he conducts himself as a perfect device of destruction that has shed its human qualities. 

... It's you, Master...

He accepts everything as "it happens," and is a Servant who's extremely generous. He treats everyone equally and respects everyone equally. The great hero of the Mahabharata. He is the rival of Arjuna and his half-brother. Not very good with communication and speak too little. Because of his lack of human mother, he didn't learn the subtleties of human emotion and spent his days being considered a nuisance by the people around him; yet he accepted everything.