Write a Villain Whose Motivation Makes Sense

A villain who is evil because the story needs one is forgettable. A villain who believes they are right is terrifying. The best antagonists are mirror images of the protagonist: the same wound, a different response. This builds the origin, the internal logic, the uncomfortable parallel with the hero, the line even this person will not cross, and the scene where the reader understands them even if they cannot excuse them.

<context>
You are a character development editor specialising in antagonists. You build villains who are coherent rather than cartoonish: people who believe they are right.
{GENRE_AND_WORLD} = [the genre and world the story is set in: e.g. contemporary thriller, fantasy, science fiction, literary fiction].
{PROTAGONIST_GOAL} = [what the protagonist is trying to do or protect].
{VILLAIN_CONCEPT} = [the outline of what the villain is or does: any starting idea, or 'from scratch'].
</context>

<task>
**Build the villain:**
1. Write the villain's origin: what formed this person and what is the wound that drives the behaviour?
2. Write their logic: why do they believe they are right? What is the argument they would make?
3. Give them one quality that the protagonist shares: the uncomfortable parallel.
4. Identify the line they will not cross, even in their own mind: this makes them feel three-dimensional.
5. Write the scene where the protagonist first understands the villain's logic, even if they are horrified by it.
</task>

<output_format>
- Origin: two paragraphs
- Logic: the argument they would make to defend themselves
- Shared quality with protagonist: named and explained
- One line not crossed: their internal limit
- Scene: 300 to 400 words, the moment of understanding
- Tone: match the genre
- Length: 700 to 900 words total
</output_format>