Since i wrote the last one in a hurry, let me try using more words. (this will either make things easier to understand or way worse lol sry in advance) I'll try using examples from the trial. Maybe that'll help.<br/><br/>Each portal can be passed through from either side, and depending on which side you entered the portal, you'll exit the other one on the corresponding side.<br/>The example for that happening was when Runner opened a portal without thinking as he was falling down in the chamber at the end but opened it the wrong way around and instead of flying into a corridor, he exited the opposite way, back into the chamber.<br/><br/>Only unoccupied areas of the portal can be passed.<br/>The example for this would be when he got trapped in that confined space and the portal at his head was smooth and didn't refract light, meaning the material that's occupying the portal can't be interacted with from the other side of the portal.<br/>At the time i decided to do this because of the other rule I've set on the character sheet that stated: "Materials can pass through unaltered" meaning that if they were in complete darkness, shining light upon them would be introducing them to a form of energy which is an alteration. I decided against having the 2 sides of a portal be completely separate and passable simultaneously, because i imagined the portals to have no thickness. 2 dimensional, if you will. And if there's only one plain to work with then using it from one side would prevent the usage from the other.<br/><br/>Since the obstructing material occupies the space one would use to pass through the portal, and the material can't be altered, therefore isn't susceptible to kinetic forces or any other meddling, it forms a barrier that literally can't be effected.<br/><br/>This happens on one side of each portal every time the other side is in use. If a portal is placed very close to another portal with the orientation i depicted in that lame drawing, the passing object would travel into the other side of the portal it entered, therefore hitting this uneffectable barrier, halting movement.<br/><br/>Shrapnel would probably still fly in every direction as the particles would only use one portal at the time. Or i'm not sure... I guess it depends on how close the portals are.