As news surfaced that Wentworth Miller has been added to the cast of The Flash, more information on Firestorm has been released!

[…] As for Robbie Amell coming on board as Ronnie Raymond — one half of DC Comics character Firestorm — reporters were quick to wonder whether Firestorm’s other half, Martin Stein, will also be making an appearance. Berlanti revealed that Stein was initially in the pilot, but was eventually written out. That said, we will meet Stein as Amell’s character evolves.

Barry’s suit was also a point of contention, as it’s not quite as vibrant as in the comics. Berlanti noted that designer Colleen Atwood went through a series of different looks and that the team will be “evolving the suit over time. … It will become more vibrant and red” as the series progresses.

Source: TV Line