Well, they can clearly be killed, as we already killed one.
I assume that they have the ability to control time and space to some degree, based on various hints we got throughout the game, which, for all their accomplishments, I don't believe the forerunners ever could.
Forerunners must think if an Endless was infected by Flood it would literally be unstoppable, Rings were the last resort against The Flood, if a Ring no longer works on Flood then that's a terrifying thought to the Forerunners, I suppose from that perspective you can see why they would imprison them but that's still fucking scummy, Lol.
There's an ending dialogue for the Legendary ending where a Forerunner AI (I think) is talking and saying how time is a construct that Forerunners cannot control and they cannot allow it to be theirs (Endless) but did they really imprison them simply because of a possibility rather than something they actually did?
JFC Forerunners are bastards. Sorta makes me feel bad about killing The EndlessLast edited by Ryuu96 - on 12 December 2021