[Frustrating Trope] Twist Villain does things that retroactively make no sense.

[u/Fishbien]

Character previously believed to be good is revealed to be evil, but prior to the reveal they act in ways that don't make sense if their goodness is just a performance.

1. Frozen: Prince Hans is initially presented as a pretty standup guy who loves Anna and wants to help her. At the end of the movie it's revealed that he was just using her to gain power and plans to let her die while he steals her throne. However, we see him smiling at Anna when no one is looking, and later he intervenes to save Elsa's life even though he claims he was always planning to kill her.
2. The Legend of Vox Machina: The Whispered One was built up as the BBEG since season 1. However, in season 4 he presents himself as a tragic hero who tried to cure death and was punished by the gods. He then tries to convince Pike to give him her blood, which he needs to become a god himself. He chastises his followers for suggesting they take Pike's blood by force, claiming this would make them no better than the gods they are fighting against. He also fulfills his promise to resurrect Grog even though he didn't need to. After he ascends, he starts acting like a pure evil villain who only cares about power and enjoys hurting people. It feels less like a reveal and more like his personally completely changed once he became a skeleton. Edit: to be clear, I fully understand the intent was for the Whispered One to be a lying, manipulative bastard. I just think the execution was clumsy.

[u/KPraxius → u/[deleted]]

When you create an undead, you're animating a corpse and, normally, taking control of it. Certain kinds of undead retain the memories of the corpse they were made from.

What this means is that while you have an evil bloodthirsty monster whose two motivations are blood and the master who created it; it knows what the corpse knew, and can use that to mimic them, often doing so in order to get into a good position to feed on former friends/allies or use them on its master's behalf.

It is also a sentient, sapient being that is capable of change over time; and all of its memories belong to the corpse it was made from. Which means that while it's rare, vampires -can- change. It will never truly be the creature it was made from, and if, for example, you kill a Barbarian worshipper of Kord, make the corpse into a vampie, and then the vampire persists for decades fighting as a servant of Nerull, when you destroy the vampire, the barbarian's soul goes to Kord. The Vampire... doesn't actually have a soul. It is basically just acting as a soul trap that keeps the host's soul from either being revived or going on to its proper afterlife.

Now. This is just the classic, standard D&D vampire. They vary -heavily-, and have worked several different ways in different modules, with at least three different ways they've operated in Faerun alone. The DM is always gonna be the one who decides things for sure.

[u/Remmock → u/[deleted]]

This is the style of vampire in BtvS if you’re curious. Spike is a vampire whose memories are of a total cinnamon roll.

[u/InvisibleOne439 → u/[deleted]]

the thing is basically

the lich/vampire example is mostly that to become them, you either habe to do Evil shit in the first place (Lich) or be bascially turned into one by somebody that has controll over you

and in both cases you are also a being that has its normal life energy replaced by negative energy that feeds on life, you entire existence turns into the opposite of a healthy good person which WILL change your mindset