Unhinged/obsessed protagonist that tries to fight for the greater good?

I recently read the webtoon Hand Jumper, where there is a character that deceives, manipulates and tricks their "friends" and foes alike for what they believe is the greater good. There is almost like a descend to madness, where they may have started on good intentions, but they are slowly getting more ruthless as time goes on. Most importantly however is that they rationalize it and still try to see themselves as a good person, even though they are starting to look at people as if they were chess pieces.

I really liked how this character was written and was wondering if anyone knew of any protagonists that are similar to what i described. I would really like to read the thoughts behind such a person and their actions. Thanks in advance!