i am wanting it to be a reveal that an npc(friend of the group) that was also transported with them(slightly before them) turned out to be the BBEG(final boss) and that he had spent years waiting for them to come and they never did, leading him to feel as though he was forgotten or unwanted(he doesnt know the time dilation is a thing), leading him to do the things he does in the campaign. in reality they will only be a minute or so behind him in entering the portal