In fiction, characters can choose many covert methods to harm others without being noticed. Here are some common and creative techniques: 1. **Psychological manipulation**: Using verbal cues or emotional manipulation to get the target to make decisions that are unfavorable to them. Characters can subtly sow seeds of discord and cause anxiety or insecurity in their targets. 2. **Poison**: Using poisons that are difficult to detect, especially those that can affect health slowly, such as in food or drink. Characters may also deliberately choose a toxin that takes time to show symptoms. 3. **Technical means**: Using technology to hack into someone's electronic devices, collect or steal sensitive information, or destroy someone's reputation or career. 4. **Social media manipulation**: Using fake accounts or manipulating social media to spread rumors about the target or leak their private information, thereby harming them on a social level. 5. **Trap design**: Carefully designing seemingly accidental incidents, such as structural failures in a house or problems with the brakes of a car, to make the injury look like an unfortunate accident. 6. **Legal loopholes**: Taking advantage of legal and regulatory blind spots to harm the other party's interests through legal means, such as designing complex contract terms to cause the other party to suffer financial losses. 7. **Using agents**: Indirectly executing plans through other uninformed or unrelated people to ensure that one's own involvement in the incident is minimized. When writing these plots, it is very important to ensure that the character's motivations and means are reasonable, which can enhance the credibility and appeal of the story.