(i have nothing to work with for chapter 3 so you'll have to just believe me here.) Theory 1! Mike is the main character in Chapter 3. @Number1Salesman said this same thing but gave no explanation (i think). but here's why i think it's true. In the 1st Chapter Jevil talks about "Queen" Who ended up being the main Character in Chapter 2 (Jevil is a secret boss). Spamton, The OTHER secret boss talks about Mike. Who, (by this theory), Will be the Main Antagonist in Chapter 3. Next Theory will be in Part 2 because my hands hurt.
Based on every Deltarune Theorist. (HalfBreadChaos on YouTube for inspiration)