Flash Exists In Both Marvel and DC!

Buried Allen.

There's a common character to both DC and Marvel and that's our good old 'Buried Alien'. Sorry, I meant Barry Allen. There was a period when 'Flash' was dead in the DC comics' "Crisis on Infinite Earths", so Marvel took this opportunity to introduce a blond speedster clad in red and yellow. Not able to remember his name or where he came from (his last memory being running, which is how Barry 'died'), he called himself "Buried Alien". 

Now, as far as I read the Amalgam Series, there's no exact reason for which the Buried Alien appeared. But there was some race between speedsters from the Marvel Universe. For obvious reasons, he won that race easily. 

Maybe the dead Barry Allen was transported into the alternate universe. 

When Buried Alien was about to win the race by a large margin, he stopped and ran back a few miles to help one another speedster who was in trouble.