Most likely, his parents, Harry and Ginny Potter, could send the howler. They would be concerned about their son's well - being and actions at Hogwarts. If Albus got into trouble or was not living up to the Potter family name, they would not hesitate to send a howler to set him straight.
In this fanfiction, Albus Severus Potter might be scolded severely in the howler. Maybe he got into some big trouble at Hogwarts, like getting caught cheating in a very important exam or accidentally releasing a dangerous magical creature in the school. The howler could be from his parents, especially if they found out about his misdeeds and were extremely disappointed.
Often, the fanfiction shows Albus Severus Potter getting a howler in a way that heightens the tension. It could be delivered by a mysterious messenger or in a way that reveals hidden secrets about his family.
There could be a fanfiction where Albus Severus Potter gets transported back in time to the era of his father's youth. He could witness the events that Harry went through first - hand, but also accidentally change some small things that have big consequences for the present time. He then has to find a way to fix the timeline without completely erasing his own existence.
In fanfiction, Albus Severus Potter often embarks on various adventures. When it comes to the mention of 'lemon' in relation to him, it might refer to a type of trope in fanfiction where there could be some light - hearted or slightly comical situations. For example, he might encounter a magical lemon that has some special powers. However, it could also be misinterpreted as something inappropriate if not used in a proper context.
Snape could also be a possibility. If Harry did something that Snape considered a serious offense in Potions class, like using an ingredient in the wrong way that could have caused an explosion, Snape might send a howler to scold him. However, it would probably also be filled with his usual sarcasm and dislike for Harry.
There's a fanfiction titled 'Harry Potter: Albus's Destiny'. It focuses on how Albus Severus Potter discovers his own unique path in the wizarding world, different from his father's. It's a great read as it shows his struggles and how he overcomes them.
I really like 'Albus Severus and the Lost Magic'. In this fanfic, Albus discovers an ancient form of magic that has been long forgotten. It's a really exciting read as he tries to master this new magic while also dealing with the regular Hogwarts drama. The way it ties in with the existing Harry Potter lore is quite clever.
There are many interesting fanfictions on this topic. Some might explore how Albus discovers his Parseltongue ability. Maybe it could be a hidden talent that surfaces during a dangerous situation at Hogwarts, like when he stumbles upon a hidden chamber with a snake - related mystery.
There's a fanfic titled 'Albus Severus in the Shadows'. In this one, Albus Severus is drawn into a dark world of magic that he didn't expect. It shows his journey as he tries to navigate this new and dangerous side of the wizarding world while still holding onto his own values. It's a really engaging read with some unique takes on the character.