In the chamber of secrets, Harry discovers that the reason that he had not been getting letters from his friend is because Dobby the house-elf ( *sniff* ) had been stealing all the letters to prevent him from going back to hogwarts. After a long and terrifying car ride with Ron, they arrive in Hogwarts and they find that the new DADA professor is Gilderoy Lockheart-some one that many people in the fandom dislike (but not as much as Umbridge). He is a complete fraud and goes around bragging about things he didn't do. After the first attack from the basilisk on Mrs. Norris, the teachers start upping security. After several more attacks that include Hermoine as victim and finally result in Ginny Weasley being taken, the teachers decide to close the school. After discovering where the chamber of secrets is, Harry and Ron, along with Lockhart, go into the chamber of Secrets to take on the basilisk. Lockhart tries to escape by firing a memory charm with Ron's broken wand but it backfires, causing him to lose his memory instead. the backfired spell causes a small eaqrthquake, leaving Harry and Ron seperated. After finding a memory of Tom Riddle, whose source of power is the diary and also drawing on Ginny's strength, it is revealed Tom is Voldemort, who summons a basilisk. Harry destroys the basilisk and the diary of Tom Riddle, which unkown to him was a horcrux. He finds Ginny Weasley and they get out of the chamber of Secrets. 

In the prisoner of Azkaban, a new character is revealed: Sirius Black, on the run from the magical and Muggle gouverment because he was framed by Peter Pettigrew of murder. This entirely new character gives Harry a new sense of family and makes all of us in the fandom grow closer to Sirius, and his demise in the fifth book made lots of people cry and alspo signified Harry's lack of any real family.

In the goblet of fire, Voldemort finally rises and in the process he has killed Cedric, an entirely innocent person, and his death signified Voldemort's mercilessness. 

Finally, in the deathly hallows, it shows how catasrophic a war can be. In the hunger games, it showed quite a lot of devastating effects of war but in the deathly hallows, since we have had a lot more time (10 years?) to grow closer to the characters and for them to develop it makes their deaths all the more tragic. Fred is killed and it left everyone crying. Dobby as well, and Remus and Tonks, newly married, as well as 50 other unamed people. Snape is killed, and at the end he reveals his true colours to Harry: he always loved Lily and was working for Dumbledore all along, and this made everyone in the fandom love him at once.