On The Flash, neither of Barry's best friends Cisco and Caitlin have been all that excited to realize they've become metahumans. Both were perfectly content to back Barry up from the safety of S.T.A.R. Labs with their intellect rather than powers. In Caitlin's case, her reluctance has made a lot of sense. Her powers affect her personality, turning her from a sweet and kind doctor into Killer Frost, a ruthless villain who is willing to kill, kidnap, and torture to get what she wants. As for Cisco, at first he simply didn't seem to want the responsibility. Over time though, he warmed up to the idea, especially after Barry gave him the name Vibe.
Cisco's reluctance to use his powers returned in season 3, after the death of his older brother Dante. While Dante and Cisco's relationship has often been strained, Cisco tried to fix it after seeing the Earth-2 version of Dante murdered. The loss of his older brother in a car crash has affected Cisco badly, nearly destroying his friendship with Barry who would not go back in time to save Dante. It's also turned the normally upbeat young man more solemn, and more unsure of suiting up as Vibe.
In the synopsis for episode 11 of season 3, 'Dead or Alive', Cisco might not have much choice in the matter. When H.R.'s life is threatened by a metahuman from Earth-19 with powers similar to Cisco's, he may be the only one who is able to save H.R. Read the full synopsis here:
DC COMICS’ GYPSY ARRIVES ON EARTH-1 – H.R.’s (Tom Cavanagh) past catches up with him when a bounty hunter with vibe powers named Gypsy (guest star Jessica Camacho) arrives in Central City to bring him back to Earth-19 to stand trial for his crime. It turns out inter-dimensional travel is illegal on their Earth. H.R. surrenders but when Barry (Grant Gustin) and Cisco (Carlos Valdes) find out that H.R.’s only hope would be to challenge Gypsy to a fight to the death, they intercede and Cisco offers to fight Gypsy instead.
True, H.R. is not Cisco's favorite person. He's annoying, not as smart as the team had hoped, and socially kind of a mess. But he is a part of the team now, and it is very much in character for Cisco to try to save him. This could also be a sign that Cisco is moving on with his grief and getting back to his life more completely.
It does seem unlikely that Cisco would kill Gypsy, unless he absolutely had to. Generally The Flash and company attempt to capture the villains they face; they kill only when there is no other choice, and often it was not the intended goal. If Cisco has to fight to the death with Gypsy, she'll certainly be trying to kill him. Whether he can defend himself without killing her remains to be seen.
The Flash returns with ‘Borrowing Problems from the Future’ on Tuesday, January 24th at 8pm on The CW.
Source: The CW