The Flash has a secret brother.
The Flash is, most often the only child of Nora and Henry Allen, however, in 1997’s Speed Force #1, a new story emerged. It alleges that on the stormy night of May 13, two different pregnant women walked into the medical offices of Dr. Gilmore in Fallville, Iowa. The doctor had been drinking heavily and had already dismissed his nurse. Alone, he delivered the child of the wealthy Charlene Thawne. The baby was strangled by its own umbilical cord and the doctor, still intoxicated, was unable to save him.
After delivering a healthy set of twins to Nora Allen, he made the decision to give one of the twins to the Thawnes. They named their son Malcolm. The Thawnes were con artists and Malcom grew up being poorly treated and taunted throughout his life, which eventually led to him seeking out revenge upon his birth family, Barry (The Flash) in particular. He developed powers through a talisman he wore on his chest and took on the alter-ego of Cobalt Blue.