The Dark Mage and the Knight of Light [Western Fantasy]

Liu Xi transmigrated into a Western fantasy novel as the villain, Siyar, a frail and brutal marquis who secretly practices black magic. His knight commander is Lang Jialuosi, an upright holy knight. After running him through, the knight will become the male lead's brother and help him overthrow the Kingdom of East. Now the male lead is already on the path to overthrowing the regime. His knight commander is about to discover that he's a black magician, and the holy knight's sword is only one door away from running him through. Question: How do I hide the dark magic circle in my room? Answer ASAP, urgent! Answer: Make the upright holy knight afraid to come in. Siyar: I'm good at this. Step one, take off your outer robe. Step two, give him a hug. Step three... The knight ran off in a panic. Lately, Lang Jialuosi has been troubled. His master has been acting more and more wantonly, but he doesn't dislike the change. His master is becoming a good lord, making the territory prosperous, and the people have started praising him. Could he just, you know, stop being so undignified all the time... Bards praise the gods, but the gods of the continent of Seze fell long ago. Ten thousand years ago, a dark elf was inexplicably summoned into a spirit body by someone from Earth. More than a decade later, he was inexplicably summoned back by Siyar, a marquis of the continent of Seze. Siyar wanted to summon the God of Darkness, but the god had long since fallen. So Liu Xi, the only remaining supreme being of darkness, was the one summoned instead. Theme: Strive for prosperity for all