What I remember about this story is pretty vague. It was a J2 au where Jared and Jensen were being trained in some sort of institute/school/military facility. Somehow they'd bonded (psychically, soul-wise, whatever) and caused this huge explosion. Everyone tries to figure out what it was, and finds out that Jared and Jensen are exponentially more powerful, but even MORE powerful if they are close or touching.

I think I remember one of the boys trying to more this huge block with their power.

I've looked through a few pages of the powers tag and found nothing, so I hope I haven't made this all up in my head. :)