Are you allowed to re-use a small percentage of a protected work?
A tough question to answer, even when you know all of the specific details! Copyright protection certainly applies to quotations. It can apply to aspects of the characters, depending on how recognizable they are. As an example, writers of "fan fiction" encounter this dilemma all the time. Doing what you are contemplating could be copyright infringement, or not. It could be protected by the fair use defense, or not. Different judges might interpret the same facts in a different way when they apply the fact-specific balancing tests of fair use.
In a nutshell, the less you "copy," or "take inspiration from" an existing work, the smaller chance that you would be caught or that the copied person would do something to make you stop. The more successful your work turns out to be, the bigger chance that the copied person will do something about it.
