There's no way to be sure without more information, but it could be a couple. One person writing the letters and the other as the recipient.
The main characters are Sophie, a young woman, Claire, an older woman, and Charlie, the man Sophie falls in love with.
Typically, in a novel like 'love letters to the dead', the main character would be the one penning the letters. This person is likely to be someone who has lost a loved one and is using the letters as a form of catharsis. There could also be other supporting characters like friends or family members who are either aware or unaware of these letter - writing sessions. They might interact with the main character and influence their thoughts and feelings as they write the letters.
Without having read the book, it's difficult to name the main characters precisely. But based on the title, it seems likely that there would be at least one character who is deeply involved in the mystery of the 'ghost letters'. This character might be a young person, perhaps someone who is just starting to understand the power of love. There could also be an older character, like a grandparent or an old family friend, who has some knowledge or connection to the 'ghost letters' and can provide some guidance or backstory. And of course, there would probably be a love interest for the main character, someone who they are either falling in love with or trying to re - connect with, and this relationship would be intertwined with the mystery of the 'ghost letters'.
Since I don't have the exact content of 'love letters and other stories', it's hard to say precisely. However, if we think about typical love letter scenarios, the main characters are often the sender and the recipient of the letters. For the other stories, they could be people whose experiences are being told, perhaps a young person on a journey of self - discovery, or an old couple reminiscing about their life together.
In the 'the watcher house letters story', the main characters might include the person who lives in the house where the letters are found. There could also be the writer of the letters. If there is a mystery involved, there might be a detective - like character who is trying to solve the mystery of the letters. Or it could be that the watcher is the main character, and the letters are a way to understand their motives or actions.
Since I don't know the exact story, it could be a young child who writes letters to God with pure faith. Maybe there's also a pastor or a religious figure who helps guide the community in their spiritual journey during Christmas and has some connection to these letters.
Since I don't know the exact 'wicked letters true story', I can't say for sure who the main characters are. They could be the people writing the letters, the recipients, or those affected by the contents of the letters.
In the 'little wicked letters real story', the main characters could be a group of friends where one of them starts receiving these strange 'wicked letters'. There might be a detective - like character who tries to figure out the origin and purpose of these letters. Or it could be a story about two rivals, and the letters are used as a tool in their rivalry, so the rivals would be the main characters. However, this is just pure guesswork given the lack of information about the story.
Since I haven't read the story, I can't say for sure. But it could be a young protagonist who discovers the 'wicked little letters' and tries to figure them out.
Since I don't know the details of this story, I can't say for sure who the main characters are. But it could be the people who wrote the letters and those who were affected by them.