Quoting a novel as a personal signature might constitute copyright violation because copyright law protected the author's creative work, including text, pictures, audio, video, and other forms of work. If you quote the content of the novel as your own signature, it may be regarded as a copy or adaptation of the original work, thus violating the copyright of the original work. Although some novel fans would use their own creativity to adapt the plot or sentence of the novel as their personal signature, this adaptation did not constitute a copy or adaptation of the original work, but only as a way to express their personal preferences, so it may not constitute copyright. However, if a plot or sentence of a novel was used for commercial purposes, such as making advertisements or promotional materials, it might constitute an copyright violation. Therefore, if you want to use the content of the novel as your personal signature, it's best to confirm whether it's an copyright violation to avoid unnecessary legal disputes.