Albedo from 'Overlord' is another character that could be popular in this crossover fanfiction. Her loyalty to Ainz and her own powerful abilities can add a lot of drama and interesting plotlines. She could potentially have some intense interactions with the characters from 'Familiar of Zero', especially those who oppose or are in conflict with Ainz in the crossover scenarios.
Louise Françoise Le Blanc de La Vallière from 'Familiar of Zero' is also popular. Her relationship with her familiar and her growth as a mage can be an interesting element when combined with the 'Overlord' universe. She might react in different ways to the strange beings from 'Overlord' and her character arc could be further developed in the crossover.
Ainz Ooal Gown from 'Overlord' is likely to be very popular. His overpowered nature and complex personality make him a central figure that can drive many interesting crossovers. He can bring his vast power and knowledge into the world of 'Familiar of Zero' and create all sorts of chaos or order, depending on how the fanfiction is written.
Ainz Ooal Gown is likely one of the most popular. His powerful and mysterious nature makes him a great character to crossover. He can bring his vast knowledge of magic and leadership from Overlord into the RWBY universe. Another popular one might be Albedo. Her loyalty and combat abilities can create interesting dynamics when interacting with RWBY characters. For example, she could form an alliance with a team in RWBY and use her skills to help them in battles.
Ruby Rose is often a popular crossover character. Her positive attitude and powerful scythe - wielding skills can bring a unique dynamic to the Overlord universe. She might befriend some of the more benevolent characters in Overlord or cause chaos with her energetic nature.
Gilgamesh is often a popular character in these crossovers. His haughty and powerful nature makes him a great character to interact with others from different universes. He can be both an antagonist and an unlikely ally depending on the story.
One interesting idea could be the interaction between the different power systems of 'Overlord' and 'Familiar of Zero'. For example, how the magic in 'Familiar of Zero' might interact with the various abilities of the characters in 'Overlord'.
Ainz Ooal Gown is often a popular choice. His overpowered nature and complex personality make him a great character to transplant into other game worlds. He can bring his vast magical knowledge and strategic thinking to new settings, which can lead to some epic crossovers.
Ainz Ooal Gown from 'Overlord' is often a popular choice. His powerful magic and complex personality make for great story - making in a crossover. In 'Gate', Youji Itami is also frequently featured. His military knowledge combined with his laid - back attitude can create interesting interactions with the characters from 'Overlord'.
Cersei Lannister could also be a popular choice. Her cunning and thirst for power in Game of Thrones could be enhanced in the Overlord fanfiction world. She could use her wits and the resources of the Lannisters to become a powerful Overlord - like figure, perhaps even making deals with the dark forces often associated with the Overlord concept.
It's hard to say for sure, but Ichigo from 'Bleach' could be a strong contender. His Hollowfication gives him a huge boost in power, and his Bankai is extremely powerful. In the world of 'Familiar of Zero', his powers would be very hard to counter. However, Louise with her Void magic also has the potential to be very powerful. Her magic is unique and can be extremely destructive when she manages to control it properly.
The interaction between Ainz and Roswaal would be fascinating. Ainz is used to being in a position of power and having complete control over his domain in Overlord. Roswaal, on the other hand, is a complex character in Re:Zero with his own motives and schemes. Their encounter could be a battle of wits as they try to outmaneuver each other, or they might find common ground in their pursuit of power and knowledge.
Definitely Naruto is one of the most popular characters. His growth from an outcast to a hero in his own world can be an interesting parallel or contrast in the Overlord universe. Then there's also Itachi. His self - sacrificing nature and his powerful Sharingan abilities can lead to some very engaging storylines in the fanfiction. From the Overlord side, Demiurge is also quite popular. His cunning and strategic mind can create some intense power plays when interacting with Naruto characters.