How does Harry react to the howler from Sirius in the fanfiction?

Maybe it's because Harry did something really naughty that Sirius needed to scold him about.

Maybe Harry was really angry or frustrated with Sirius and wanted to express it strongly. A howler gets the point across!

Maybe Harry was really angry or frustrated with something Sirius did and wanted to express his strong feelings in a dramatic way.

Well, Sirius could get really flustered. It could lead to some comical or tense moments depending on the context of the fanfiction. The howler might reveal something he doesn't want others to know.

In some fanfictions, Sirius might use it as a chance to show off his independence. He could read the Howler out loud in front of his friends, laughing at his mother's old - fashioned views. This would show that he doesn't care about her threats and is proud to be different from the rest of the Black family.

Voldemort might initially be furious. He's not used to being challenged in such a blatant way. He could try to destroy the Howler immediately in a fit of rage.

His mother could send the howler. In the wizarding world, mothers can be quite fierce when it comes to family reputation and she might be unhappy with Sirius's actions or friends.

In such fanfictions, it often leads to intense emotional moments and revelations. Harry might be shocked or confused initially.

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.

Harry might be initially shocked and embarrassed. A Howler is a very public form of scolding, and in front of all his friends and classmates, it would be a humiliating experience for him.