One great 'servamp crossover fanfic' is 'Servamp and Black Butler: A Dark Alliance'. It combines the unique vampire lore of Servamp with the Victorian setting and complex characters of Black Butler in an exciting way. Another interesting one could be 'Servamp meets Fairy Tail: Magical Encounters' which brings the Servamp vampires into the world of Fairy Tail's magic and guilds.
I really like the ones that focus on character interactions. Imagine Lambo from 'KATEKYO HITMAN REBORN' meeting Kuro from 'SERVAMP'. Lambo's childish and unpredictable nature combined with Kuro's laid - back but protective attitude towards Mahiru could lead to some really hilarious and heartwarming scenes. These crossovers often bring out new sides of the characters that we don't usually see in their original series.
One great place to find servamp crossover fanfiction is Archive of Our Own (AO3). Just search for'servamp crossover' on their site, and you'll get a bunch of results. Some popular crossovers might include ones with other popular anime series like 'Kuroshitsuji' or 'Tokyo Ghoul'.
A common theme is power struggle. When servamp characters cross over with another universe, their powers often clash or complement those of the other characters. For example, if crossed with a post - apocalyptic world, they might struggle for dominance.
One great fanfiction is 'The Unlikely Bond' which delves deep into the relationship between Hyde and Licht. It shows their complex dynamic and how they grow to understand each other more. Another one is 'Hyde's Redemption in Licht's Eyes' which focuses on Hyde's journey towards redemption with Licht being a key part of it.
First, you need to decide which two (or more) universes you want to cross over. For example, if it's Servamp and Harry Potter, study the lore of both. Know the rules about vampires in Servamp and magic in Harry Potter. Then, think of a unique plot that can bring the characters together in an interesting way, like a dark magic that affects both worlds and forces them to interact.
Another fanfiction worth checking out is 'In the Shadows of Lawless and Licht'. This one focuses more on the emotional side of their relationship. It shows how Licht's past experiences influence his interactions with Lawless, and how Lawless, with his carefree nature, gradually breaks down Licht's barriers. The story is filled with tender moments and emotional depth.
Another one is 'Vegeta in the Harry Potter World'. Here, Vegeta has to adapt to the magical environment. His initial confusion and then his determination to master the magic (in his own way) is really fun to read. The way he interacts with the Hogwarts students and teachers is full of comical and exciting moments.
I really like the 'god of highschool crossover fanfic' that involves a crossover with 'One Piece'. Imagine the 'God of Highschool' fighters sailing on the Grand Line. The fanfic might explore how their powers would fare against the Devil Fruits and Haki in the 'One Piece' world. It also delves into the different cultures and the idea of friendship and adventure in both worlds, which is really interesting.
There's also 'Naruto and the Rinnegan Legacy'. This fanfic delves deep into the lore of the Rinnegan and how Naruto fits into it. It explores how Naruto uses the powers of the Rinnegan not just for fighting but also for unifying the ninja world. The character development in this fanfic is quite remarkable as Naruto has to adapt to this new power while still staying true to his original self.
One great 'Lucina crossover fanfic' is 'Lucina in the World of Fire Emblem Heroes'. It has an interesting plot where Lucina gets transported to the Heroes' realm and teams up with various characters from different Fire Emblem games. The story is full of action and character development.