Ruby would probably be both curious and cautious. Her adventurous spirit might make her want to learn more about this strange new entity, but her sense of responsibility for her team would keep her from being too reckless. Weiss would likely be initially dismissive, thinking it's some kind of trick or a new enemy that can be easily defeated with her skills and Dust magic. Blake would be more on guard, her past experiences making her more aware of hidden threats. Yang would probably be the first to want to throw a punch, seeing Slender Man as a direct threat to her and her sister.
The RWBY characters could interact with Slender Man in various ways. For example, Ruby might be the first to sense something is wrong due to her keen senses. She could try to attack him directly but find that her attacks seem to pass through him. Weiss could use her glyphs to try and contain or at least slow him down. Blake might be more cautious, observing his behavior from a distance to figure out his motives. Yang, on the other hand, would probably charge in head - first, only to realize that brute force doesn't work against him.
Bart would probably be both scared and curious. He might initially try to play pranks on Slender Man, but as things got scarier, he'd realize he was in over his head. Lisa, on the other hand, would likely try to research Slender Man to find a scientific or logical explanation for his existence.
Sasuke would likely be on high alert. He'd immediately analyze Slender Man's movements and try to find a weakness. He might start by using his Sharingan to see if he can detect any patterns in Slender Man's attacks.
A possible plot idea is that Slender Man is a creation of an ancient and dark experiment in the RWBY world that went wrong long ago. Now he has re - emerged and is seeking revenge on those who originally created him. The RWBY team gets involved when they discover that his actions are endangering the safety of the entire world. They have to battle not only his physical form but also the psychological fear he instills in people. Slender Man could also have the ability to manipulate the nightmares of the RWBY characters, which adds a whole new level of horror and psychological thriller elements to the fanfiction.
Neville would be terrified. Having faced his own fears in the wizarding world, Slender Man's appearance would bring back all those insecurities. Ginny, on the other hand, would be more defiant. She has had her own experiences with dark forces and would not be easily intimidated. The Weasley twins might see it as an opportunity for some new pranks, though they would quickly realize the seriousness of the situation. Hagrid would be confused as he has never seen such a strange creature in the Forbidden Forest. He might try to approach Slender Man in a friendly way at first, which could be a dangerous mistake.
Well, perhaps there could be a fanfic where Slender Man is actually an ancient evil that was sealed away in the RWBY world long ago. And due to some recent events, like the opening of a certain relic or a powerful magic spell gone wrong, he is released. The RWBY characters then have to figure out his weaknesses by researching old legends. Or it could be that Slender Man has a connection to the White Fang. He uses their anger and desperation to his advantage, secretly manipulating them to do his bidding while the RWBY gang tries to stop this new threat.
Slender Man child fanfiction differs mainly in the perspective. Regular fanfiction might focus on adult protagonists dealing with Slender Man in a more 'grown - up' way, like through investigations or complex psychological battles. In child fanfiction, it's about how kids experience the horror. It's more innocent yet also scarier in a sense as children are more vulnerable.
No, the Slender Man is not real. It was created as a fictional character in an online Photoshop contest. But the stories and the idea of him have had a real impact on people, especially in some disturbing cases where people were influenced by the concept and did bad things.
They would probably be very intrigued. RWBY is used to their own fantastical world, and seeing the world of Spider - Man through fanfiction would be a new and exciting experience.
For action - heavy fanfiction, Yang would be all in. She loves a good fight scene and would be on the edge of her seat. Ruby would also enjoy it, seeing Spider - Man's heroic deeds.