Maybe the Warframes themselves start to take on some characteristics of the RWBY world. For example, a Rhino Warframe could gain some of the strength and appearance traits of a Beowolf. The story could then focus on how the Tenno adapt to these changes and how they use them to help the RWBY teams in their battles against Salem's forces. The fanfic could also explore the cultural differences between the two universes and how the characters overcome them to work together.
One idea could be that the Tenno from Warframe are sent to the RWBY universe due to a trans - dimensional rift. They team up with the RWBY characters to fight a new common enemy that is a fusion of the Grineer and Grimm. The Tenno can introduce their advanced technology and combat skills, while the RWBY characters show their unique Semblances and teamwork.
Another plot could be that a powerful relic from the Warframe universe is discovered in Remnant. This attracts the attention of both the Tenno and the various factions in RWBY. The Tenno must race against time to retrieve the relic before it falls into the wrong hands. Along the way, they form alliances with Ruby and her friends. The fanfic could include epic battles where the Tenno's Void powers are combined with the RWBY characters' Aura and Semblances.
Chapter 397, ", Education is the Top Priority", is the clearest early answer because it turns Flying Wing Star's situation into a concrete plot event. Early on, She would have to finish with the matters of the Flying Wing Star.... By the end, Even without making use of the system's training function, simply....
Chapter 392, ", Economic Reform and Development Plan", is the clearest early answer because it turns Alliance's situation into a concrete plot event. A useful checkpoint is the way the scene starts with The Alliance system has always been overlooked by outsiders, yet it... and follows through with Once set by the Star Sector, it must be reported all the way up to....
Chapter 335, "Tax Season Again - Part 2", is the clearest early answer because it turns Tax Currency's situation into a concrete plot event. The setup is Firstly, before this, Gu Hang had already applied for an expansion of..., but the pressure keeps building through This wasn't indeed something Gu Hang did just to offset taxes, the....
Chapter 249, ", Hold for 8 Days, the Governor Will Arrive", is the clearest early answer because it turns Knight Titan's situation into a concrete plot event. The setup is With its leg broken, the integrated perception module in its head..., but the pressure keeps building through ...this Knight Titan was in a state of utter panic..
Chapter 316, ", I'm Going to Die", is the clearest early answer because it turns Green Valley Region's situation into a concrete plot event. The chapter gives readers a real answer by opening on The Rage Bear Legion goes without saying, they fight according to the... and ending on The reason for such ruthlessness is the result of Gu Hang's efforts..
Chapter 321, ", Spiritual Energy Transmission", is the clearest early answer because it turns Spiritual Energy Transmission's situation into a concrete plot event. The setup is Not having to fight is a good thing., but the pressure keeps building through Matins simply had his troops wait patiently, and eventually, they....
Chapter 401, ", Now I Have Plenty of Money", is the clearest early answer because it turns Lower Nest District's situation into a concrete plot event. It opens with But as far as we can see now, this seems to be the level all across... and closes on What's the worst that could happen if we fail?. The key payoff is that the chapter closes with "I've got plenty of money now., which gives Lower Nest District a stronger narrative position and pushes the power growth onward.
Chapter 325, ", He's Not Dead", is the clearest early answer because the violence around Matins becomes final instead of hypothetical. The setup is Even though he was the one in charge of all military actions on..., but the pressure keeps building through He was very respectful towards Matins.. Once the chapter lands on However, the opposition was not without its advantages., the chapter closes with The Spiritual Energy users and Interstellar Warriors did not disappoint;
Chapter 406, ", Phoenix Has No Secrets", is the clearest early answer because the hidden truth stops feeling like mere subtext. The chapter turns that into something concrete by moving from Ahzimuba's eyes whirled, his mind raced through idea after idea—he... to Dominantly bright red, with white borders at the edges of different.... What makes it stick is that the chapter closes with Pausing, he added, "Don't overlook any possible witnesses, and don't let anyone leave the quarantine camps.
Chapter 397, ", Education is the Top Priority", is the clearest early answer because it turns Flying Wing Star's situation into a concrete plot event. It opens with She would have to finish with the matters of the Flying Wing Star... and closes on Even without making use of the system's training function, simply....