Barry stands on the outside of a bubble. All is white void. Brightly colored beacon in a sea of nothingness. He has alternated his frequency to the point of transcending human form. Now he is just as he imagines himself to be.
Alone in the void for eternity, never aging, never getting hungry, or sick. He eventually stumbles across the silvery, primordial matter, quicksilver, the reflective ink of the cosmos. Fashioning it into a device to assist in processing information, he eventually molds an area into a hatch, complete with lab and cosmic treadmill, just to stay in shape.
With this new mercurial material he is able to view and eventually interact with the DCU, which is on a lower level of exsistence than he is. Beyond death, underworld, and the furthest reaches of space, Barry Allen sits and performs experiments on a science he must develop on his own. Trapped above all matter, standing just outside the barrier of all energy, he watches and develops a plan.
He has to get Hal's help. It was his sacrifice, his turn to evil, the acceptance of carrying the burden, the responsibility to unplug existence from the lower realms of thought. It was the only way they could help this Universe grow and expand until it could find its own equilibrium. In the meantime, they'd have to find a way to keep the fire burning.
Hal relit the sun. He repositioned the galactic center towards Earth, around us. We were reshaping everything and yet I don't think even Hal could see what was happening. But I saw the pattern. I knew how they would turn on each other, suffer each in their turn. But I saw how it would help them in the end.
I need to make sure there are Flashes around to sustain the structure of this universe of ours. So, I'll build a school. Or inspire someone to build a school.