So yeah I just wanted to bring another theory here. I don’t take credit for it but I found it interesting and It was said by angry joe (yes yes I know) but anyway
The theory is based around guilty spark.
So if you dont know (I didn’t even know) this well you’ll know now. So yeah apparently guilty spark didn’t die after he took may spartan laser shots (beast of an ai). Sometime after that he (scraps of him) was found by members of the unsc and they took him aboard for questioning about I believe the forerunners, ancient humans, didact, librarian. But as always with interrogations it doesn’t go well and guilty spark takes over the ship, puts the crew to sleep and escapes after saying that he knew where the librarian was. And that’s pretty much it, they don’t mention what happened to him but I believe now we may have a hint.
Now looking back at what we know about guilty spark we know that he has a habbit to hum different tunes. I was listening to a 10 hour guilty spark video (I don’t recommend) and it has many of the tunes that he hummed.
One tune in particular strikingly resembles the same tune that cortana was humming during the legendary ending of halo 5. When I first saw the legendary ending a couple of times I didn’t think much of the humming but I now realize it just wasn’t out there to be put there, its has a strong meaning. Also in that ending was a halo array activating as she was humming which is strange because she never was the type to hum anything.
Guilty sparks main goal is to activate the halo array to wipe out the flood but his plan was stopped when chief came and beat him. The theory is that after he escaped from the unsc ship he somehow or in someway met up with the librarian. After meeting up with librarian he got synced or put into the domain and when cortana also got into the domain he took control of her and is now controlling her. Looking at the chief and cortana interaction in halo 5 where she cries I kind of got the feeling that maybe she wasn’t doing everything of her own will.
