You can try fanfiction websites like Archive of Our Own (AO3). It has a large collection of fanfictions from various fandoms, including 'Millennium Earl x Allen' ones.
Some fanfictions focus on the idea of redemption for the Millennium Earl through his interactions with Allen. In these stories, Allen might be the catalyst for the Earl to see the error of his ways. Maybe Allen's unwavering belief in the good of people starts to make the Earl question his own motives and actions, leading to a series of events where they both grow and change.
Well, it depends on personal taste. If you're a big fan of the 'Millennium Earl' series, it might be interesting as it offers a different take on the existing story. Some people enjoy fanfictions that explore new relationships and scenarios within the established universe.
There could be many interpretations in such a fanfiction. Maybe the Earl has some complex motives behind hugging Allen. It could be a moment of false kindness, where he's trying to manipulate Allen in some way, perhaps by making Allen lower his guard.
One great Harry Millennium Earl fanfiction could be 'The Unlikely Alliance'. It explores an interesting scenario where Harry and the Millennium Earl team up against a common enemy. The characters are well - written and it keeps you on the edge of your seat.
Maybe some new character interactions. Since it's a fanfiction, it might introduce unique conversations between the mana walker and the Millennium Earl that we haven't seen in the original work.
The plot might also be that the Earl's hug is a way to get Allen on his side. He could be trying to convince Allen that there is a different path than the one he's currently on, and this hug is the first step in that persuasion.
You can start by checking out fanfiction websites like Archive of Our Own or FanFiction.net. Just type in 'Harry Millennium Earl' in the search bar and a whole list of relevant fanfictions will pop up.
One possible theme could be family. As Allen is the earl's son, his relationship with his family, especially his father, would be a central aspect. Another theme might be duty. He has the duty to uphold his family's name and status. Also, identity could be a theme. Allen may be trying to figure out who he is beyond just being the earl's son.
There are some fanfics that focus on Allen Earl's growth in power. They might describe his training sessions in more detail, and how he overcomes his weaknesses. Maybe he discovers a new form of Innocence or a unique way to use his existing powers. These fanfics often add exciting new elements to his character development.