What could be the content of the Howler Harry gets from Voldemort in the fanfiction?

It could be Dumbledore. He was always one to oppose Voldemort and a howler from him would be a very interesting plot point. He might use it to taunt Voldemort or to try and make him second - guess his actions.

Perhaps Sirius is scolding Harry for getting involved in something risky, like sneaking into the Forbidden Forest. He might be worried about Harry's safety and uses the howler to convey his strong emotions. In the fanfiction world, Sirius could also be using the howler to give Harry some crucial information about his family that he has just discovered and wants Harry to know right away.

In the fanfiction, the howler could be from an unexpected source. Maybe it's from a long - forgotten enemy who has finally found a way to get to Voldemort. The howler's message could be a warning about a new threat that is coming his way, something that could even be more powerful than him. So Voldemort has to decide whether to ignore it or take it seriously.

Well, it could be about him getting into trouble at Hogwarts. Maybe they scold him for sneaking out at night or getting involved in a dangerous adventure without permission.

It could be Professor Snape. He often had a contentious relationship with Harry, and if Harry did something that Snape thought was particularly wrong or against school rules in a way that affected Snape's interests, he might send a Howler.

The Howler might contain Harry's anger and defiance. He could be yelling about all the harm Voldemort has caused, like the deaths of his parents and many others. It could also include threats of how Harry will stop him once and for all.

It could lead to all sorts of chaos! Maybe Voldemort gets really angry and lashes out.

It could be about Draco's performance at Hogwarts. Maybe Lucius is disappointed in Draco's grades or his behavior towards other pure - blood families' children.

In this fanfiction, Harry might be publicly scolded by the Howler in a really embarrassing way. Maybe it reveals some secrets about him that he didn't want others to know, like his insecurities or small mistakes he made.

Well, it could be scolding him for his association with the 'wrong' sort of wizards, like the Potter family perhaps. His mother might be furious about his choices that go against the pure - blood supremacist views of the Black family.