Basic Tips To Write Better Chosen Ones
In every other fantasy story, there is a Chosen One. Xe can alone defeat the Big Bad and save the universe. Unfortunately, Chosen Ones are incredibly easy to completely bork up.
Ask yourself whether you really need a Chosen One
If you can restructure your story so that it does not involve a Chosen One, you probably should. The general concept of a Chosen One is considered by many to be a discredited trope, so unless you really need it for your work, try to avoid it.
Make the future uncertain
If you've decided you need a Chosen One, make sure that the outcome is uncertain - ie, that there is a chance that the hero could completely fail in xir quest. Alternatively, your character's Chosen status needn't imply victory at all - see Harry Potter, Avatar: The Last Airbender, and Buffy the Vampire Slayer.
Do not use your character's Chosen status as a substitute for actual motivation
Some chosen ones - particularly evil chosen ones and dark messiahs - have no real reason for doing anything other than they've been chosen to do it. Whether your character is good or bad, try to make sure xe has (or gets) some personal motivation for doing whatever it is xe is doing.
Do not use your character's Chosen status as a substitute for actual skill or practice
Don't have your character successfully bumble through everything because Destiny says your character must succeed. Also, don't have your character become an instant expert at whatever is needed to save the world - enhanced abilities or natural talents are all right, but your character should still have to work for xir skills. (And please, no mastering skills that normally take years to learn in a matter of weeks or days.)
Don't make your character's life as the Chosen One constant pain and misery
This isn't to say that life as a Chosen One should be all sunshine and roses - in fact, it shouldn't. However, most people have a 'wangst threshold,' where if the character is surrounded by too much angst and drama, the audience will lose interest in the character. Where it falls varies depending on the person, of course - but very few people want to read a story that's nothing but angst and drama.
Make sure your character has a life and identity outside of being the Chosen One
Give your character has hobbies, activities, and people to hang around that have absolutely nothing to do with being the Chosen One, and let your character enjoy them. Make your character a person who happens to be a Chosen One, not a Chosen One who happens to be a person.
Don't make your character the ultimate solver of all problems
No matter how Chosen your character is, xe does not need to solve all of the problems all of the time, let alone get the last hit in every fight. A hero who can fix all of the problems all by xirself runs a high risk of becoming boring very quickly. Give the supporting cast a chance to shine, too.
Avoid use of the term "Chosen One" in-story
It sounds rather cheesy and narmy these days.
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