Warning: This article contains spoilers for much of the media mentioned. Also, may get a little rambling.
You've probably had a moment where you're enjoying a piece of media, and there's a character. They may not be great, they may be someone you like, but they're not hate-worthy. Then they do something. It might be small, it might be large, it might not be acknowledged in-story, but that something makes you LOATH them on a deep and instinctive level ever after. Nothing else that happens will redress that single action, that one misstep, that betrayal. Often this kind of thing is deliberately constructed, but when it isn't, it's more interesting. It shows that perhaps the writers didn't intend for this to happen, but it happened anyway.
For the example that got me thinking about this way too much, I shall have to spoil a key plot twist in Final Fantasy XV, a video game that...has more than its fair share of problems. The central cast is all-male, and one of them is the bodyguard Gladiolus Amicitia. He's...alright. Looks like a bruiser, but actually enjoys a good book. Hopeless at cooking, a swordsman, and has a strong camaraderie with his charge Noctis Lucis Caelum. During Chapter 9 of the narrative, stuff happens and Noctis's childhood friend and love interest Lunafreya Nox Fleuret is murdered. Right in front of him. And another companion, Ignis, is permanently blinded. Weeks after Noctis also lost his father. And he is then shouldered with a god-given destiny he doesn't understand. On a train to their next destination, Noctis is in shock and mourning. And what does Gladiolus do...?
Gladiolus Amicitia takes Noctis by the scruff of the neck, seems about to punch him, heckles him for "moping", tells him to "get over it", and remains some level of antagonistic towards him for...doing what I'd guess at lot of young adults do when they've suffered that level of emotional trauma. This moment, this single moment, made me hate Gladiolus. His attitude is emblematic of an extremely archaic approach to the aftershock of unexpected death and the need to mourn. It's an attitude I can't stomach at any price. No matter how much the game tries to redress this, it doesn't acknowledge that what Gladiolus did is physical and emotional abuse.
For reasons I can't fathom, Gladiolus remains popular among the fan base. For me, I'd have happily seen him die a pointless and painful death, and have another character like Ravus or Iris take his place in the foursome. This action is the stuff that I've seen loads of other characters narratively punished for so many times, but here it's just given a pass. As if the writers are saying "It's okay to physical abuse, heckle and shame someone out of the mourning process". Maybe not the intended message, but that's what it's espousing here, and nothing afterwards seems to contradict it.
Be it noted, betrayals or bad things you see coming from a mile away, or deliberately unsympathetic characters, don't fall into this category for me. Burke from Aliens is a character who seems to be on Ripley's side, but he's Weyland-Yutani, so you know he'll do something questionable at some point. Malvolio from Twelfth Night is a pompous fop who rapidly earns ire by belittling the Fool when he's trying to comfort the countess Olivia, and he's a comedy relief "villain" anyway so he doesn't count.
By contrast, let's look at Ran, Akira Kurosawa's last epic and a film I've only seen once but still love. It's a loose adaptation of King Lear, so not much explaining to do. The main thing the film succeeded in doing was first establishing Ichimonji as someone who was misguided but not malevolent. But as the film wears on, we get a growing increment of events that, for me at least, made his downfall at the hands of his disloyal sons a fitting punishment. When he dies at the film's end, I didn't feel that bad for him. I felt bad for his remaining loyal son Saburo, killed pointlessly. The long-suffering Kyoami, who curses the whole family. The loyal general Kurogare, who sees his master's plans disintegrate due to an act of indirect revenge from Lady Kaede. The young Lady Sue, butchered on the road. The blind Tsurumaru, left alone in a castle ruin waiting for Sue's return. Next to all that, Ichimonji's death seems deserved by the end.
That's a slow-burn variant of the same thing I saw with Gladiolus, although in Ichimonji's case just narrative deserts were meted out. There is also a novel storyline which somehow manages to pull this while also keeping my interest in the character strong.
Jonathan Stroud's Bartimaeus trilogy, of which I shall never stop singing praises because it's an excellent book series, has its main character Nathaniel grow from a relatively innocent boy to a spoiled and arrogant magician. By the third book Ptolemy's Gate, he is actively cruel to his supernatural servants including the djinn Bartimaeus, and has no sympathy for commoners who seek equality with their magician overlords. I deeply disliked him, so when the story SOMEHOW managed to redeem him partially when he freed Bartimaeus instead of torturing him for information as he was heavily persuaded towards, it broke some of the conditioning which made him like this. His actions still aren't fully forgivable, he admits that, and at heart he's still something of a child, but his actions during the climax of Ptolemy's Gate which includes sacrificing himself while saving Bartimaeus are almost like a combined redemption and just deserts for his actions as part of the magician's hierarchy.
I feel like Nathanial's partial redemption is one of a few exceptions to this phenomenon, because I genuinely couldn't find that many off the top of my head. Especially as in most cases I could think of, the story actively acknowledges that what the character has done is...bad. Just think about the actions of Leo in House of Flying Daggers. He goes from a sympathetic officer colleague to a jealous rival, up to attempting to force himself on heroine Mei, turning him from at least semi-sympathetic into a vile creature who suffers perhaps the worst punishment by the film's tragic climax; disillusionment and abandonment.
And in that word, we reach the nub of this strange situation. "Tragic". Each of the narratives I've mentioned have something which is more or less tragic, regardless of whether the story acknowledges it. And if it's the right kind of thing, not some magical whatsit or sci-fi dodad, it hits harder and makes things feel worse when the story doesn't punish it. A friend or lover turning into an abuser? It's scary because it can happen in real life, and as people outside the story we can't intervene. A foolish father and former warlord getting his comeuppance? Fine for him, but what about all the collateral damage. A boy schooled in a cruel and elitist system? Just look at any rich family to see potential examples of THAT happening, without any "commoner" friend or magical companion to whisper in your ear and wake your conscience.
Things like that twist our perceptions of a character, and it's a technique often used in positive aspects to garner sympathy or empathy. But it's rarer for it to be used to make the audience truly hate someone. Rarer still for it to be done on purpose. Maybe I'm reading too much into this, but it's something I can't come back to without thinking about this. One of the books I recently completed has a character inspired by Gladiolus, and... Well, let's just he doesn't get away with what he does.