/jp/ - Otaku Culture

So I just finished Dies Irae, please confirm some things for me
>Merc tells Reinhard that to destroy foreknowledge they will create the castle, fill it with souls, wait until the universe resets, absorb the souls in the new universe and repeat until the universe explodes due to having so many souls on the same place and a new universe can be born
>Reinhard somehow wasn't bored with the ide of spending 60 years doing nothing except looking smug in the castle, and was okay with the plan of spending billions of years doing nothing for some reason
>the route you play is canonically chosen by Merc when he plans what to try in the next universe
>first two routes eventually end like the Rea route normal end where Rein fucks Merc up and Merc starts creating the new universe but this time Marie doesn't show up
>Mercs endgame is the Marie ending all along
Also, why was lending his body to Trifa even needed?
Is it ever stated in other material what a world emanated by Reinhard would be like?
If foreknowledge is a thing how could Merc have been surprisised by Trifa and Marie doing stuff?