Multiple Chapters

A conclusion to a multiple-chaptered fic should be long and explain each important character's ending (and possibly death). There can be a hint to the future but the ending should be absolute for the main characters. You should make sure you satisfy the readers since they've stuck with your story all this time, It's very important that your ending matches with the tone of the rest of your work. If it's been happy and silly, then it doesn't make a whole lot of sense for the end to be extremely serious and you may end up pissing off your readers if it does swing wildly like that last minute. If you've written something incredibly angsty with the intent of a good ending, I'd recommend a more serious way of putting it, making it clear that the characters had to suffer a whole lot to get there but now they get to be happy and imply a better future. If you wrote an angsty piece with the intention of a bitter ending then keep it somber.