Lex was raised by his abusive father, to survive at any means. He also had lots of rage and anger inside him, that rage drove him to brutally beat his boarding school friend to a pulp. His desire to solve and understand Veritas (A way to control Clark AKA the traveler) drove him to madness, even to the point of killing his own father. Once Lex found out who the Traveler was he tried to control him, he thought he would be saving mankind from Clark, but instead brought the whole fortress down on top of himself. Lex came back paralyzed and hidden from society only to be killed by Green Arrow. Lex had cloned himself so that he could rebuild his body, in the finale he was rebuilt. In a meeting with Tess Mercer (Lex's Sister)he stabs her thinking that he wis saving her from becoming him. In her last moment she infects Lex with a neurotoxin that will erase all his memory, Cuts to a sequence of all his bad memories getting erased, his finale memory is Clark and him the fortress.
Now wouldn't Lex be a good man with everything that made him evil gone, tell me what you think.