It would greatly affect her relationship with Emerald and Mercury. They might be confused as to why Cinder is so interested in Pyrrha. Emerald could feel jealous, thinking that Cinder is replacing her with Pyrrha in some way. Mercury, on the other hand, might just be indifferent or find it strange.
One possible fanfiction idea could be that Cinder and Pyrrha are long - lost sisters separated by some dark event in their past. In this fanfic, Cinder could be on a journey of redemption after realizing her sister is Pyrrha. Pyrrha, on the other hand, might struggle with the idea at first but then come to accept Cinder. Their relationship could develop as they face common enemies in the RWBY universe.
In a fanfiction centered around their sisterly bond, Cinder and Pyrrha might have a telepathic connection due to their sisterhood. This could be used in battle situations, like when Pyrrha is in trouble, Cinder senses it and comes to her rescue. Their bond could also be a source of inner strength for both of them, especially in the face of the great challenges in the RWBY world.
In RWBY fanfiction, Salem and Cinder often have a complex relationship. Salem is a powerful and manipulative figure. She sees Cinder as a useful tool. Cinder, on the other hand, is ambitious and craves power. She is willing to do Salem's bidding in order to gain more power for herself.
One possible plotline could be that Cinder starts off secretly admiring Pyrrha's combat skills. Maybe she spies on Pyrrha's training sessions and tries to learn from her techniques. This could lead to a situation where Cinder has an internal struggle between her admiration for Pyrrha and her own dark motives in the main RWBY storyline.
Cinder is often portrayed as complex. Her usual cold and calculating nature might be softened in fanfiction when it comes to her relationship with Pyrrha. She could show vulnerability that she doesn't usually display. Pyrrha, on the other hand, is typically shown as the more empathetic and moral one. She might be the one to reach out to Cinder and try to understand her motives.
The relationship can start with conflict. For example, Cinder might see Raven as a threat to her plans, and Raven might see Cinder as a dangerous and unpredictable force. Then, through a series of events like battles or encounters where they have to work together against odds, they start to respect each other's strength.
One possible storyline could be a redemption arc for Cinder through her relationship with Pyrrha. Maybe in an alternate universe, Cinder realizes the error of her ways and Pyrrha helps her to change. They could start as enemies but gradually come to understand each other.
To write a compelling interaction, start with a strong contrast in their personalities. Ruby is optimistic and pure - hearted, while Cinder is cynical and power - hungry. Have them meet in a situation where their goals conflict, like when they both are after a powerful relic. Ruby could try to reason with Cinder, appealing to her better nature (if there is one). Cinder, on the other hand, could mock Ruby's naivete while secretly being intrigued by her unwavering belief in good.
For the RWBY team, it could boost their confidence. They might feel more in control of the situation and be more proactive in future battles. For example, Weiss could become more determined to protect her kingdom now that Cinder's threat seems lessened.
Cinder would probably win. She has a wide range of powerful abilities like her fire - based powers. She can also be very strategic. A Beowulf, while strong, is more of a brute force creature. Cinder could use her speed and intelligence to outmaneuver it and then finish it off with her powerful attacks.