1. In Harry Potter and the Chamber of Secrets, Snape brews a powerful potion called the Polyjuice Potion, which allows Harry and his friends to disguise themselves as other people. Harry uses this potion to impersonate Draco Malfoy and obtain information from the Slytherin common room. While Snape's intention is to help Harry gather crucial information, the process of brewing the potion is dangerous, and it could have resulted in serious consequences if not done correctly.
2. In Harry Potter and the Prisoner of Azkaban, Snape is the Potions master and teaches Harry and his classmates how to brew various magical potions. Some of these potions have potentially harmful effects if not prepared properly. Snape can be strict and demanding as a teacher, but he also ensures that the students follow safety precautions and learn how to handle dangerous ingredients responsibly.
3. In Harry Potter and the Half-Blood Prince, Snape becomes the Defence Against the Dark Arts professor and teaches Harry and his classmates how to defend themselves against dark magic. Throughout the year, Snape provides Harry with valuable information and training that help him face various challenges. However, there are also instances where Snape's teaching methods are harsh, and he can be verbally abrasive towards Harry.
It is important to note that while Snape's actions can sometimes be risky or unpleasant for Harry, he ultimately plays a crucial role in protecting him and helping him achieve his goals. Snape's complex character is marked by both his personal conflicts and his dedication to protecting the greater good.