Perhaps Ruby would use her skills to become a sort of vigilante in the real world. She could see the crime and injustice around her and decide to take action. Since she has her combat training from Remnant, she'd be very effective. But at the same time, she'd be constantly at risk of being discovered and having to deal with the legal consequences of her actions.
Ruby would need to adapt to the food in the real world. In Remnant, they might have different kinds of food based on their regions and cultures. Here, she'd be introduced to a whole variety of new tastes. She might find some things delicious, like pizza perhaps, but also be really confused by things like fast food chains. Also, she'd have to get used to the currency system. Without any money at first, she'd have to figure out how to earn or get some in order to survive.
One idea could be a story where Ruby and Coco team up for a special mission. Maybe they have to infiltrate an enemy base, and Ruby's speed and Crescent Rose combined with Coco's fashion - inspired weapons and strategic mind make them an unbeatable duo.
One idea could be that Ruby and Jaune are partnered for a special mission outside of Beacon. Ruby's speed and combat skills combined with Jaune's strategic thinking could make them a great team. For example, they might be sent to investigate a mysterious Grimm activity in a far - off village. Ruby can quickly scout the area with her speed, while Jaune plans their approach based on the information she gathers.
One idea could be Ruby discovers she is the Winter Maiden in a moment of great danger. As she tries to control her new powers, she has to face off against Salem's minions who are after the power of the Maiden. Ruby's friends, Weiss, Blake and Yang, are initially shocked but quickly support her in her new role.
One idea could be a story where Neo and Ruby are forced to team up during a special mission in a mysterious new area. They start off distrusting each other but gradually learn to work together as they face various challenges.
Well, one plot could be that Ruby's mother faked her death and is actually alive in hiding. Ruby discovers some clues that lead her to believe this and goes on a journey to find her mother. Along the way, she has to face various challenges and enemies who are also after her mother for their own reasons.
One idea could be a story where Ruby and Scarlet team up to face a new, powerful Grimm that has unique abilities. Maybe it can manipulate time, adding an interesting twist to their battles.
In some 'rwby dark ruby fanfiction', there might be the idea of Ruby being corrupted by an ancient evil force. This could lead to her having to fight against her own nature as she is slowly turned into something she hates. It can also show how her friends try to save her from this dark path, which makes for a really engaging story.
Another idea is a time - travel fanfic. Cinder travels back in time and meets a younger Ruby. She could try to manipulate Ruby into following a different path, but Ruby's strong will and sense of justice might resist. This would create a lot of conflict and interesting character dynamics as Cinder tries to change the future and Ruby tries to protect it.
Perhaps in the fanfiction, Ruby's new status as the Red Dragon Empress makes her a target. Salem could send her most powerful minions after Ruby, thinking that if she can control or eliminate her, it would tip the balance in her favor. Ruby would then have to learn to master her powers quickly while also relying on her team for support.