One common theme is adventure. The male reader often goes on adventures with the RWBY characters, which helps to build relationships. Another is the development of the harem. This includes the male reader getting to know each girl in the RWBY group better over time.
One popular 'rwby x male reader harem fanfiction' is 'RWBY: A Male Reader's Adventure'. It has an interesting plot where the male reader character gets involved with the RWBY girls in various exciting adventures. Another good one could be 'Male Reader in RWBY's World: Harem Quest' which focuses on the male reader building relationships with the different RWBY characters in a harem - like setting.
One idea could be that the male reader is a transfer student to Beacon Academy. He has a unique Semblance that catches the attention of the RWBY girls. For example, his Semblance could be related to time manipulation. Ruby might be intrigued because she loves unique abilities and wants to learn from him. Weiss could initially be a bit standoffish but as she sees his skills and determination, she warms up to him. Blake would see something in him that reminds her of her own struggles, and Yang would be attracted to his confidence.
Emerald Sustrai could be an interesting choice. She has a complex backstory and her skills as a thief could be a source of intrigue. The male reader could be the one to help her turn away from her more villainous ways. Also, Penny Polendina would be a unique addition. She is an android with a kind heart. Her naivete and eagerness to learn about human emotions could make for an interesting relationship with the male reader.
Some fanfics focus on the male reader being from a different dimension and Raven is intrigued by his out - of - this - world knowledge. This creates a bond between them as they try to understand each other's worlds better. These types of stories often have a lot of character development for both Raven and the male reader.
One idea could be that the male pirate reader's ship crashes near Vale. He then meets Team RWBY and they initially mistake him for a threat. But as they get to know him, they find out he has valuable knowledge about some ancient Grimm - related secrets that could help them in their fight. So they form an uneasy alliance at first which gradually turns into a strong friendship.
One great fanfiction is 'Blake's New Beginning' where the male reader character enters Blake's life at a crucial time. It shows their relationship developing gradually through various adventures. The story does a great job of staying true to the RWBY universe's essence.
One common trope is the 'accidental encounter'. For example, the male reader might accidentally bump into a female character and that starts their initial interaction which could lead to a relationship. Another is the 'protective male' trope, where the male reader has to protect the female characters in his harem from various threats.
One common theme is friendship. The male reader often forms strong bonds with the RWBY characters. For example, going on missions together and relying on each other in tough situations. Another theme is self - discovery. The male reader might be figuring out his place in the RWBY universe, his powers, or his purpose.
One great fanfiction in this category could be 'The Encounter with the Female Grimm'. It has an interesting plot where the male reader character stumbles upon a unique female Grimm. The story is filled with action and adventure as they interact in a post - apocalyptic RWBY world.