Writing characters from other people's novels in one's own book was a common way of writing, also known as plagiarism. Although this behavior may be regarded as a creative inspiration, it may also be regarded as immoral or copyright violation. In the process of writing a novel, copyright laws and other relevant laws should be followed to prevent the unauthorized use of other people's works. If you intend to use characters from other people's novels in your own novel, you should first obtain their explicit permission or use other legal methods to quote their works. Although it is possible to write characters from other people's novels in one's own novel as a way of writing, one should treat this behavior with caution and abide by copyright laws and other relevant laws.