Quote Originally Posted by Cheesegear View Post
But my point is; "Free Will + Time Travel to the Past = No Fixed Outcomes."

If time moves forward - and only forward - we can only make choices based on the knowledge we have.

If we could go back to the past, with new knowledge, hypothetically, we could change the past.
"If you could live in any time period, when would you live?" ...That hypothetical which gets asked all the time, assumes you would live in the past with the knowledge you have now. You can change a lot.

In hard sci-fi? No. You would hit the time-traveller's paradox. You can't go back to the past to change things if there's no past to change.

In soft-as-jelly sci-fi? So soft it borders on fantasy, rather than sci-fi. You can change anything you want.
Time-travel in 40K is seemingly random. Anyone could go back to any point in time, at any time. That means anyone can time-travel. Why not someone who matters? It's very...Convenient...That no-one who matters has time-travelled. They might actually change something.
In a setting confirmed to have time travel, isn't it reasonable to assume the timeline already incorporates any efforts by time travellers to change the present? You can't change the past, because you are already part of it and time travel is generally a one off thing, you don't get a second go,* and even if you did that second go is also already part of the timeline.

*Unless you're Abaddon that one time he went to a daemon world where time flows backwards.