She could interact through communication. If she's smart, she might learn their language or find a way to communicate with them through technology. For example, using a special device to translate their beeps and boops into English.
Interaction can also be physical. If she's brave enough, she could help with repairs on the Transformers. Maybe she climbs up on Bumblebee to fix a damaged part. This would require a lot of trust from both sides. And during these physical interactions, they can exchange stories, like she tells Bumblebee about her life on Earth and he tells her about Cybertron.
The interaction could be really dynamic. The Twins are known for their banter and they might include the fem reader in it. If she's a feisty character, she could give as good as she gets. Maybe they'll have moments where the Twins show off their Transformer abilities to impress her, and she'll respond with her own skills or knowledge. They could also have some misunderstandings at first due to cultural differences, but gradually work through them.
It can greatly expand the reader's view. By reading fanfiction, they see different takes on the characters. For example, a fanfiction might show a more vulnerable side of Optimus Prime, which could change how the reader perceives him. It can also introduce new storylines that make the Transformers world seem more complex and multi - faceted.
Another possibility is that the fem reader is in a dangerous situation, and the Transformers rescue her. From there, she decides to join their cause. She could learn about their history, their struggles, and in return, she offers them a new perspective on humanity. Maybe she helps them make better decisions when it comes to interacting with humans, and they all grow together as a result.
One possibility is that the fem reader is a scientist studying Cybertronian technology. The Twins are sent to protect her because her research is important. At first, they don't get along well because of their different natures. But as time passes, they come to respect each other. The fem reader could introduce new ideas to the Twins about how to use their abilities in different ways, and they in turn show her the wonders of their Transformer culture.
The Autobots could see Ben as an interesting new ally. They might be initially cautious, but as they see him use his Omnitrix to transform and fight, they gain respect for his abilities. Ben, on the other hand, would be in awe of the Transformers' size and power. He could learn from them about advanced technology and use that knowledge to upgrade his Omnitrix. The Decepticons would likely see Ben as a threat or a tool to be used. They might try to capture him or the Omnitrix. Ben's alien forms could have different interactions with the Transformers. For example, XLR8 could be used to quickly scout out Decepticon bases, while Diamondhead could provide a strong defense against their attacks.
He might be cautious at first. Vergil is used to dealing with demons and the like, not giant robots. But once he realizes they're not a threat (or if he decides they are an interesting challenge), he could start to communicate. Maybe through some form of telepathy or just by gestures.
The characters could interact through battles. For example, Bakugo might see the Transformers as a new challenge and try to blow them up with his explosions. He would be amazed by their durability at first. Then he might start to strategize how to take them down. On the other hand, the Autobots could see Bakugo's passion and potential and try to teach him about teamwork, which is something he struggles with.
They could interact through combat. For example, the Autobots' powerful blasters and physical strength could be combined with RWBY characters' unique weapon - based combat styles. The Autobots could provide cover fire while the RWBY characters get in close for more precise strikes.
The technology from the Transformers universe would likely have a huge impact on Remnant. The RWBY characters would be amazed by the Autobots' ability to transform and their powerful weapons. The Autobots, in turn, might be intrigued by the concept of Aura and Semblances.
Well, Iron Man and Ratchet might start off on the wrong foot. Iron Man, with his cocky attitude, might try to show off his tech to Ratchet, who would be unimpressed and critical of Stark's technology in comparison to Cybertronian tech. But they could later come to respect each other's skills.