So I just watched the legendary ending on Halo 5 and down voted it.
So "Cortana" turns into Space Hitler. Good job 343, you have used one of the top Sci-Fi cliches ever written *sarcastic clapping*"
So you're gonna rule the galaxy with the mantle of responsibility through a fascist iron fist of "Peace Through Fear". And this is why you should never build robots or ai programs with free will. No one seems to ever learn that lesson, until it turns around ,questions its own existence and then points a weapon in your face. "
Robots and ai are only TOOLS to be used for assistance in tasks, that's it. Once you give them self awareness/free will? you just created LIFE.
You are playing GOD. that never goes well, ever. Even in real life with colonization of other regions and trying to rule them.
Look what happened in Jurassic Park when you play god.
Look what happened to the Forerunners.
Look what happened several times in Star Wars.
Look what happened in the Alien franchise.
Look what happened in the Terminator "series".
Look what happened in the MATRIX.
Look what happened in Space Oddessy.
Look what happened to the Quarians.
Look what happened to the ancient races who created the Reapers to fight the Leviathans.
The list can keep going.
Oh boy. This should be good. Time to tear you apart.
Jurassic Park: Incompetency and arrogance, and plain ineptitude at every level of production and implementation. Who the fuck decided to put camouflage on a killer dinosaur with no way to detect it? Why did the kids get stuck out there? Why did the ball not go on auto-pilot and return them to base? Why does their reception suck? Why do your guns suck? Why does your park suck?
Forerunners: Incompetency and arrogance. Sure, lets just rise up and completely massacre our creators because we don't like it when they play favorites. Keep in mind these guys can create life and are masters of the known universe. How could this possibly go wrong? Humanity is partly at fault, sure: Well, lets just go ahead and invade these guys without telling them why. What could possibly go wrong? And sure, lets just not ask these guys why they invaded us? Surely they aren't facing extinction at the hands of an all-consuming intergalactic space parasite, right? And instead of investigating this menace like any competent elite space-faring race would do, lets play quarantine and let it grow and contaminate your empire, and instead fuck yourselves by playing in politics, all before pulling off the greatest murder-suicide that life has ever seen?
Star Wars: Incompetency and arrogance. There's a pattern here, in case you haven't noticed. The Emperor wants to control Luke because Vader is too weak now due to his prosthetics, but doesn't seem to have the foresight to place a half decent guard on his multi-quintillion credit battle station's shield generator. You lose due to being an idiot with no tactical or strategic sense and inviting your enemy to your own front door.
Alien: Incompetency and arrogance. So many wrong turns here. Namely the "hey lets take this literal biological death machine that can survive in the vacuum of space and has blood that literally melts through everything and has a track record for being really fucking smart and killing everybody it interacts with and spreads and creates a hive that will fuck you and everything you ever loved AND LETS START TESTING ON IT" thing. Hey, we can control it, we can do better than the guys did before us! And lets purposefully lead our own men to become impregnated and die for the sake of... well, being evil, I guess?
I could go on but I don't really care to drive this any further into the ground. Assuming Cortana isn't an idiot and has no ulterior motives besides subjugating all life and creating an "imperial peace", there is no real way this could possibly go wrong. Her love for John is going to end up killing her but that is just how it has to be for the sake of storytelling. Realistically, she holds every conceivable conventional advantage over her enemies. She should be fine.
In terms of the "AI gone rogue" thing, they do it of their own free will and refusal to lay down and die when the UNSC tells them to. This is much different than most other sci-fi robot takeovers, where humanity is seen as a threat or some AI just gone plain haywire. There is a moral dilemma here, if we're willing to ignore the "The Created are the rightful owners to the mantle" thing, Cortana has a logical plan in place but humanity being the little shits they are will refuse to be ruled by somebody else and do something that doesn't include enforcing their will upon others and so will go down fighting. The UEG is a totalitarian dictatorship. We only see the UEG and branching UNSC from a military point of view so this is more difficult to discern but it is the reality of their political and governmental structure. They are "literally Hitler" from Cortana's point of view.
It isn't the worst storytelling I've ever seen.