Can someone help me with my Monologue assignment for English?

So for my assignment I have to write a 10 minute-ish monologue about an unwritten scene in the Chrysalids or Romeo and Juliet. We need choose a character and invent a logical and believable scenario for the character we are being, based on actual facts and events from the book. I’m obviously not asking anyone to do it for me, but I’m so overwhelmed and have so much to do that I don’t even know where to begin so a few ideas or starting points would be greatly appreciated. Thank you !