DC’s version of Captain America's super soldier serum exposes a secret ingredient the MCU never will. In 2011’s The Flash #3-4, the Scarlet Speedster encountered an old friend who had received an “upgrade” thanks to a unique version of the super soldier serum, and as the Flash digs deeper, he learnsed of this serum’s background.

Super soldier serums, or substances that enhance normal people to superhuman standard, are a staple of comic books. Indeed, DC's ultimate assassin Deathstroke was enhanced by a program explicitly intended to create "super soldiers." However, the most famous by far is Marvel's version. After being administered to Steve Rogers, the serum transformed him, raising him to the maximum possible human potential. Despite the serum's singular nature, this has not stopped other organizations in the Marvel Universe from trying to replicate it - usually with disastrous results; for example, Man-Thing was created in...