Evil is something many characters get caught up in. Evil Feels Good and you might go over the Moral Event Horizon. Many come to a Heel Realization and perform a Heel–Face Turn to fight for the side of good, likely being The Atoner and wanting to redeem themselves for their crimes.
Then, there's this character. He has redeemed himself in the eyes of the heroes, his sins have been forgiven and he is welcome again. There may even be some truly forgiving characters who insist he never needed forgiveness, he just had to turn back from evil. But he will have none of it. The sins he has committed and the people he's harmed, he's done too much to simply let go of it. He denies his own redemption.
This character may still be The Atoner, trying to do enough so in their own eyes they are eventually redeemed. Or they may be of the opinion that they can never be redeemed. Either way, expect a lot of self-hatred and disgust, and they may become The Aloner, refusing to work alongside the heroes but still aiding them from afar, unable to face them. Despair Event Horizon may be an issue if the character was a hero who turned evil and now has realized how far they've gone.
In extreme cases, the character may realize they are evil and have committed many crimes, but will continue being evil anyway because they see no chance for redemption and will not even try. There is still a chance for them though, if they come to see there is hope for redemption and it is not too late to change their ways.
Not to be confused with Redemption Rejection, when a character is offered the chance to reform and refuses it. Inverted form of Reformed, but Rejected, which deals with a reformed character still being rejected by the heroes -- in this trope, he is reformed but rejects himself.
Merrick in Power Rangers Wild Force, who provides the page quote. After acting as a Duke Org named Zen-Aku during a stint of Brainwashed and Crazy, he gives the above quote and initially refuses to work with the Rangers. At the end of the series he begins Walking the Earth to come to terms with things.
Gabranth in Final Fantasy XII at the very end of the game. With everything else of value stripped from him, he has nothing else to fight for but his hatred of his brother Basch, and thus continues to act as an antagonist until Basch convinces him to find his pride again and aid them in defeating Vayne. Gabranth does help, but is fatally wounded during the fight.
In the spin-off Dissidia: Final Fantasy, Gabranth is fully this trope, staying in a purgatory dimension instead of returning to World B because he finds no hope in the Vicious Cycle of war going on their ending.
Also in Dissidia, Golbez refuses Cecil's offers to join him and the heroes. He's not evil at all and Cecil knows this, but Golbez considers himself unfitting to serve the light.
Riku has shades in Kingdom Hearts II, unable to face Sora and own up to his evil deeds in the first game, while he combats the forces of darkness on his own. That he delved so deep into the powers of darkness he's taken on the form of the former Big Bad Ansem is also a big factor. He becomes an Anti-HeroAtoner at the end of the game and in 3D, though still harboring doubts.