Western Crossover: Why Not Destroy the World?

My name is Mifa Peitra, a mutant who can control the earth and occasionally transmigrate through time against my will. I've watched my companions die right before my eyes, and I've been driven to the brink by the world itself, unleashing apocalyptic disasters. Then an organization called the “Time-Space Administration Bureau” punished me. My powers were sealed, and I was handed over to a mercenary in a red-and-black bodysuit with a mouth that never stops running: Deadpool, Wade Wilson. I became his “person under supervision.” From then on, my whole life went completely off the rails. I was forced to enroll in school and start learning to read from scratch; Wade tortured me with extra-spicy tacos, and I had to learn how to “politely” say no with a dagger and a pistol; Looking at my unreliable guardian and this even crazier multiverse, I fell into deep thought: So why didn't I just destroy the world back then? Oh, right. I tried, but failed. The day Deadpool found Mifa, his to-do list started getting updated: 1. Teach an illiterate kid to read 2. Attend that damn parent-teacher meeting 3. Stop the person under my supervision from destroying the world on a whim Mifa: “Geology today. Where should I bury someone tomorrow?” Deadpool: “Thanks for asking. I'm busy babysitting.” #Working hard (under duress) to protect the world today too# (1. The early chapters are a little heavy. If that's not for you, skip to Chapter 11. The main text is in third person. 2. I only give the protagonist cheat powers. Deal with it. The protagonist isn't a saint; this is a coming-of-age story, not research-heavy, loosely based on canon, with significant alterations. 3. There are a few System-binding plot points in the middle, but the System is fake.)