Begin by making a list of the elements from both RWBY and Elder Scrolls that you love the most. This could be specific characters, magic systems, or locations. Then, find a way to combine these elements in a way that makes sense. For example, if you like the Grimm from RWBY and the Daedra from Elder Scrolls, you could create a story where the Grimm are somehow related to the Daedra. Next, start writing the opening scene. Make it engaging, perhaps with a bit of action or an interesting dialogue. And as you write, keep in mind the voices of the characters. They should stay true to their original personalities from RWBY while also being able to adapt to the new situations in the Elder Scrolls world.