It might be harder than we think - are there any ghosts in HP who simply wanted to be ghosts? It seems more like an involuntary thing, people who are too afraid of death to cross over.
Nearly Headless Nick I believe mentions that he made a choice when he died, and can't unmake it. That implies volition in the moment.
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My motto: Repensum Est Canicula.
Originally Posted by turkishproverb
I am not getting into a shootout with Golentan. Too many gun-arms.
Leiningen will win, even if he must lose in the attempt.