Remember Me tetralogy

Remember Me is a Fantasy/Horror book series written by American author Christopher Pike. The series centers around what a recent high school graduate, Shari Cooper, does after dying, having been murdered at a friend's party. Remember Me (1989) Remember Me is a New York Times national bestseller. Shari Cooper had almost graduated from Hazzard High. Jo, Shari's best friend, is into the paranormal. When Shari goes to Jo's house to pick her up for the big party, Shari ends up finding pieces of paper that were a short story written by Peter Nichols, Shari's friend who had died. Coincidentally the girl's name in Peter's story was Ann, which Shari thinks has something to do with her, because that is her middle name. During Big Beth's party they play with a crystal and they are convinced Peter is talking to them. Shari finds out that her boyfriend cheated on her, and goes out onto the balcony to get some fresh air, and the next thing she knows she is waking up in her own bed. She goes downstairs to have breakfast with her family, but she can't pull the chair out and her parents and her brother Jim are ignoring her. Shari Cooper is dead. The only thing Shari Cooper can remember is falling off her friend's balcony during the party. Shari Cooper's death is seen as a suicide, but she knows that she was murdered. Peter Nichols, also a ghost, attends Shari's funeral. Finally reunited, they comfort one another. They try to figure out who murdered Shari. Jo brings out the ouija board to contact Shari, but another force takes charge of it and tells them that Peter and Shari are burning in hell. A shadow chases Shari into the cemetery and when she runs into Peter, it disappears. Jo feels that Shari blames her for her death. Shari has a dream that tells her everything she needed to know: Shari was switched at birth by Jo's mother, a nurse. Jo and Shari are half sisters, while Jim's girlfriend Amanda is actually Jim's biological sister. Amanda knows about the switch, but is still in love with Jim. She attacks Jim so that no one else can have him; Peter intervenes, but his shadow attacks him and he falls to the floor. Shari learns that Peter is vulnerable to the shadow because he killed himself. Together they fight back against the shadows, and help save Jim's life.