You are sitting by a lake. An old man gives you a piece of hot dog and says to use it for fishing. You decide to go fishing in your lake. You catch a small minnow. With that minnow, you catch a bluegill. With that bluegill, you catch a large catfish. You go to the ocean. With the catfish, you catch a shark, with that shark, you manage to catch a megalodon-like shark. With that giant shark, you catch the attention of aliens. You give them the shark in exchange for access to their home planet. You go to their planet and enslave their entire race.
You go fishing on their planet and get similar results. You enslave enough races to piece together a ship using their technology that can essentially warp anywhere near instantly. Soon, you have enslaved the whole galaxy and make earth the capital. You decree yourself supreme ruler of the galaxy. By this time, you are mid aged. You use the ship to go to another smaller galaxy and enslave that one.
You put your intergalactic rule to good use by making the other races farm and mine until each planet is inhabited. Though you are supreme ruler, you are fair and well respected. You have grown quite old, so you assemble the greatest minds in the galaxy on now the capital solar system’s main planet, earth. They work together to find a way to give you near infinite life by harnessing the sheer energy of a black hole. As they do this, they make all of spacetime immortal as well. As You continue to conquer galaxies peacefully, but now that you have the most powerful army of over nine hundred quintillion elite lifeforms, you take the galaxies by brute force.
Trillions of years pass. Technology advances to a point that you could conquer a galaxy in a few weeks, to a few days, then hours, then minutes, then seconds, then near instantaneously. While back then there were duodecillion of unexplored galaxies, you have whittled it down to only about a trillion unconquered in the universe. You decide to bend the space-time continuum and create a portal to another universe. It takes only a few thousand years before your vast conquest can expand to another universe. What time it used to take to take over a galaxy now is the time to take over a universe.
As your subjects grow however, so does rebellion. The first great war only lasts a few millennia though, because your army is so immense. You once again assemble the universe’s great minds, but these elite are trillions of times smarter. They get to work on larger weapons, faster portals, and better ways to keep the peace. This movement succeeds, but you are now conquering universes faster than you can find. Soon, you are finding a few universes to conquer every few years instead of plank seconds. You come up with an idea.
Soon, you have made a universe generating machine. It takes the universe's hidden in every atom and brings it out. This can do googol universes a plank second, so you still manage to conquer them within a few quadrillion years. To keep up with this, you create a matter making machine that holds a universe each. Even then, the process of conquering is incredibly slow for you.
It has been nearly googleplex years, and your immortality is wearing off. You decide to do one more thing as ruler of spacetime. You revert all that you had done into the way it was before. You still maintain your age though. Finally, before you die, you see a boy sitting by a lake. You hand him a hot dog and tell him, “Here, try fishing with this!”