5) Cobalt Blue
One must-have character on the series – if for nothing more than the intense emotional implications – is Cobalt Blue, Barry Allen’s long-lost twin brother.
While it initially sounds quite a bit like something out of a soap opera, Cobalt Blue’s existence is believable enough that, with enough care and planning, it could be pulled off on the series quite nicely.
On the night of Barry’s birth, two women came to the hospital: Nora Allen and Charlene Thawne. Charlene’s child had been strangled by its own umbilical cord, and the doctor in charge was too intoxicated to save the baby. Nora gave birth to twin boys and in an attempt to remedy his mistake, the doctor gave one of them to Charlene, and told Nora that her child was stillborn.
The Thawne baby was named Malcolm, and grew up in a life of crime. He eventually finds out that he’s adopted and is fueled by a jealous hate for him. He comes in possession of a mystical talisman that his adopted family used for their crimes, which creates a blue flame that can steal anything that your heart desires. Eventually, he begins to wear the talisman on his chest and becomes the supervillain Cobalt Blue.
So far, The Flash has placed Reverse Flash as its series-long antagonist, as he’s responsible for the death of Barry’s mother. Eventually though, things with Reverse Flash will come to a head and the series will need a new villain. Cobalt Blue could easily fit that role, and could offer yet another emotionally-charged foe for Barry to face off with.