I have a few theory's, one of which is this; Remember when we were all pushing him off with the grenades... They added "bumpers" Like strike bowling where are the bumpers? They are on the side of the lane right?... But there is no bumpers at the back... What happened when we pushed off Templar... What happened when they patched it? They stopped us from pushing Templar at all, but they didn't take the ability to push ATHEON using solar grenades... I think that we could push ATHEON off the back of the temple room between the glass pillars referring to ATHEON as the needle that threads through time... Time can be relative to the VOG itself and we are not in the VOG but in "time" meaning that wherever ATHEON is he is in time... He controls time.... Ok theory 2: I have witnessed the portals opening after we defeat ATHEON with no one stood on them. I have also witnessed someone walk into "mars, or past" portal get marked as you do when you pass through. Next thing was another fire team member plus myself walked into Mars with no marking. We were not marked.... Possibly having a specific portal open at the end of the fight closes it... However they reopen. It could be the last portal in which you exit is the one to go through, or the opposite. E.g leave mars - kill ATHEON - mars stays open, or mars is not able to then mark you after he dies, or vice versa. I have never been with a group looking for secrets but I would love too....