Kaeya

You can trust only the half of what he says, at best. Destined for greatness and grandeur... and to hide ugly realities behind a layer of charm and elegance. He believes he has made a clean break with his past, but one day fate will catch up with him. When it does, he will have a major decision to make. Major trust issues and loneliness.In the Knights of Favonius, Kaeya is the most trusted aide for the Acting Grand Master Jean. You can always count on him to solve any intractable problems. Not everyone in Mondstadt loves Kaeya, but no one knows what secrets this witty, charming knight has...
An accomplished swordsman and a strategic thinker in the Knights of Favonius, rumored to hail from beyond Mondstadt.
Kaeya is an outwardly confident and charming individual with a flair for drama. He is sometimes seen as overly laid-back and even lazy, but he takes his work seriously. He is surprisingly popular among the elderly of Mondstadt, even earning himself the title of "top candidate for grandson-in-law." His charisma and determination have earned him the admiration, respect, and favor of many people in Mondstadt — yet, his love for provoking others has also gained him the exasperation of those same people. Kaeya also enjoys putting people into high-stress situations and challenging their values, which he does to both his enemies and his allies alike. He takes pleasure in seeing the hesitation in his comrades' eyes at the moment just before they dive into battle with him, just as he takes pleasure in the look of fear in his enemies' eyes as they face off against him.
He seems to get a kick out of telling bold-faced lies and convincing others to do his work, but this serves him well in his role in the Knights of Favonius. He is a self-proclaimed "anti-hero with an attitude problem;"[2] as long as everything ends the way he wants, Kaeya does not care about the methods used. Still, according to his informant Vile, he draws the line at working with those who threaten others