Spoilers for the Season 3 Finale
Disclaimer: I don't own anything.
The first time Cisco sees a speedster's hand vibrate, it's in a dream. A creepy, weird, blue tinged dream, but a dream nonetheless. He can't hear Caitlin whispering that he's going to have a stroke, can't see the lines on Joe's forehead crease, or feel Barry's hand on his shoulder. He does remember the Harrison Wells saying he was Eobard Thawne, remembers the first time he confessed to the murder, remembers hearing himself screaming that he's going to kill him and help him please, but he remembers nothing as vividly as that hand pulsing through his body straight to his heart. Some nights, that vision comes back and he wakes up sweating, tachycardic, and has to put his hand over his heart to remind himself that it's still there.
The second time Cisco sees a speedster's hand vibrate, it's still Thawne's but this time the world is in full blown color. He tries to get a confession out of Thawne but he won't give. And then he starts walking towards Cisco, with his outstretched right hand. One step, then another and he can almost feel that hand vibrating through his rib cage into his heart. Cisco tripped back into the trap.
Oops.
He thought he could do this, for Barry, for himself, for the team, but now that he's in the moment, now that the hand is almost upon him, he hesitates. But then he pulls out his button, activating the force field.
And all fake Harrison does is laugh.
Fake Dr. Wells steps through the forcefield as if it wasn't even there. And Cisco can confidently say panic set in. He's paralyzed, stuck on the spot. His palms are sweating, and his lungs won't seem to move. The hand is at his shirt when the bullet hits Thawne. He thanks God for Joe West to this day. Strangely this is the day he stops completely trusting Barry Allen because Barry tried catching the bullets to get a gosh darn confession. He was going to let him die for a confession. Everything is suddenly moving too fast. The bullet lodges in Well's chest just as the hand touches his shirt. Well's collapses to the ground, Barry screaming in frustration, Joe is still standing with his gun raised, and Caitlin bursts in the rooms, her heels clicking loudly on the tile floor. And then Caitlin's soft hands were on him, checking for injuries. He can still hear her low pitched whisper.
"Are you okay?"
And of course he isn't. A hand was almost put through his heart. Cisco wouldn't sleep for the next month.
The second time he sees a speedster's hand vibrate, it's when Wally gets his powers. He's happy for Wally he truly is, but why, on this Earth, or any Earth for that matter, did he have to use his right hand? The same hand that Eobard Thawne had tried to push through his various cartilage and tissue in real life? And why is Wally holding it at chest level? The perfect level to cause critical damage. Barry doesn't notice, continues on with the conversation. But Cisco's eyes widen, he slumps down on his stool and his hand automatically goes to his heart. He rubs his chest, as if about to have a heart attack. Caitlin notices, makes a move towards him but he can only stare at her. She relents, giving him space to breath.
The third time he sees a speedster's hand vibrate, it's when evil Barry asks him to make a splicer. He lowers his hand slowly. This Barry remembers Cisco's shock that night, remembers his trembling at Eobard's hand. This time Cisco doesn't tremble, he watches, as slowly, slowly, the hand advances towards his chest. It takes Barry exactly four point three seconds during which time Cisco has two thoughts. One: Maybe now he'll get to see Dante and they can finally reconnect and be bros. Two: He really loved this jacket, another article of clothing ruined, speedster's are so reckless. But evil Barry stops before lodging his hand in and says something that knows will hurt him so much more. He points over to Killer Frost, and Cisco knows, knows what he would do to her.
The fourth time he sees a speedster's hand vibrate, it's still evil Barry's, but this time he's in his top notch optimus prime armor. Evil Barry's right hand is holding his throat, keeping him from running. His mouth opens and closes, like a fish's. He can't speak; this time he knows he will die. His last regret was that he couldn't save Caitlin Snow. She has been there for every time a speedster's hand has come in contact with Cisco's body and this will be the last time.
Or so he thinks.
And before Evil Barry can even get his hand to his chest, a blast of frost overpowers him. Killer Frost helps him up and for once, rather than grabbing his chest, he grabs her hand.