It's a New Year. The sun shining, the snow is melting, and all around people are burying old feuds. Forgiveness is in the air.

But some feuds can never be forgiven.

This week, I want to read a story with roots as old as time. Once, they were the best of friends. Now, they are the worst of enemies. Ceaser and Brutus, Anakin and Obi Wan, Professor Xavier and Magneto.

Your story must include two characters who were/are/will someday go from being the staunchest of allies to the most the hated of rivals

There's plenty to work with here, this is some classic shit. Betrayal. Love. Mothers turning against sons and brothers against sisters. Any genre, any time period, the disagreement can be anything, so long as it matters to your characters more than the world itself. Make it sad, make it epic, make it a story that stands the test of time. Don't be boring.

You don't have to include the entire arc (in fact, you probably shouldn't), but by the time the story is finished, the reader should have a pretty good idea of where the characters have been, where they're going, and what has torn them apart.