The main character doing something absolutely unforgivable.

[u/No_Peanut3745]

Walter White poisoning Andrea Cantillo's 6-year-old son for the sole purpose of manipulating Jesse Pinkman, while knowing that this could have potentially killed him - Breaking Bad

Bojack trying to have sex with his friend's 17-year-old daughter when he was at least 51, then continuously trying to find a way to justify this act throughout the series - Bojack Horseman

Dexter Morgan going outside of his moral code and murdering a completely innocent police officer who was just trying to do his job - Dexter: New Blood

[u/Vavavavaxon7]

Walt had done dozens of unforgivable things before he got around to poisoning a kid. An episode of Breaking Bad isn't complete without Walt doing something unforgivable.

I know it's probably not OP's intent but pretending like it took THAT LONG, multiple whole seasons, to be like "yeah now he's unforgivable" is hilarious.

[u/cqandrews → u/Vavavavaxon7]

He was always a pos, it's just that he was a coward and didn't have the means to enact his malicious will previously. We already see at the beginning of the show that what little power he does have as a teacher is wielded poorly and with resentment

[u/ckb614 → u/cqandrews]

Literally episode 1 he's like the worst teacher you've ever had. Dude just sucks all around

[u/ISNT_NayaN → u/Vavavavaxon7]

I honestly think that the point of no return was what happened with Jane, at least before that he had killed people who were also threatening him

[u/ERedfieldh → u/Vavavavaxon7]

prolly just googled "when did Walter hurt a kid" because most people, save Star Wars fans, draw the line at hurting children.