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.
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.
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 417, ", All Forces Attack!", is the clearest early answer because the buildup finally cashes out in a real clash. A useful checkpoint is the way the scene starts with Compared to the Seven Horse Treaty, the collection of Imperial Tax is... and follows through with Regardless of my wishes, I don't have the authority to agree to such.... By the close, The Green Skin Orcs of the Iron-Tooth Clan have been ravaging the..., and the chapter closes with Tan Jiuyi let out a sigh.
Chapter 350, ", Tens of Millions of Troops", is the clearest early answer because it turns Lambert's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Following the governor's request, the number of defending forces in... and follows through with She desperately hoped it wouldn't come to that..
Chapter 415, ", Steel Wing Star Battle", is the clearest early answer because the buildup finally cashes out in a real clash. The chapter gives readers a real answer by opening on Under such circumstances, human troops must be deployed for defense... and ending on And this behavior of the Green Skins significantly disrupted 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. Early on, In the past, during the many battles on Rage Owl Star, his troops.... By the end, The dispute arose when Luman told Gu Ming that out of the eight.... Inside the broader faction conflict storyline, the chapter closes with "Hold for eight days.
Chapter 362, ", Unforgettable Forever", is the clearest early answer because it turns Orbit Sinister Energy's situation into a concrete plot event. It opens with The scheduled strike time has arrived, please give your... and closes on Ammunition was lavishly spent, they even suffered the cost of.... The key payoff is that the chapter closes with One more chapter, but later in the night, which gives Orbit Sinister Energy a stronger narrative position and pushes the power growth onward.
Chapter 352, ", Swimming Upstream", is the clearest early answer because it turns Swimming Upstream's situation into a concrete plot event. A useful checkpoint is the way the scene starts with In the face of a full retreat, there was actually a legion moving... and follows through with For a time, the Rage Bear Legion's dispatched vanguard forces,....
Chapter 439, ", Temir No.5 Meat Grinder", is the clearest early answer because it turns Green Skin's situation into a concrete plot event. A useful checkpoint is the way the scene starts with The war situation on Temir No.4 was progressing basically as planned... and follows through with This would be the third force under Gu Hang's control, apart from the....
Chapter 355, ", I Promise You", is the clearest early answer because it turns Tianma Fleet's situation into a concrete plot event. The setup is In the process of the advance, the 35th Brigade experienced losses., but the pressure keeps building through Although the orbital strikes had created a path for them, their....
Chapter 333, ", Father King, The Times Have Changed", is the clearest early answer because it turns Alliance's situation into a concrete plot event. It opens with The chief steward representing the old King, much like the previous... and closes on I reiterate to you the Alliance's conditions once again.. The key payoff is that the chapter closes with 4.4k, which gives Father King, The Times Have Changed a stronger narrative position and pushes the family politics onward.
Chapter 333, ", Father King, The Era Has Changed", is the clearest early answer because it turns Father King's situation into a concrete plot event. The setup is Eureka was still pondering over the role of the political commissar..., but the pressure keeps building through Eureka Pambos?" Eureka raised his head a bit uncomfortably, as it was....