The Flash’s alter ego, Barry Allen (played by Grant Gustin), is zipping into The CW’s Arrow this Wednesday at 8/7c, and he’s making fast friends with Oliver’s Girl Friday, Felicity.

So how will Starling City’s vigilante deal with the younger competition? How different is the show’s incarnation of Barry from others you may have seen? And what’s the future of the Flash pilot?

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Following a screening of Arrow‘s fall finale (airing Dec. 11), executive producers Andrew Kreisberg and Greg Berlanti, writer/DC Comics Chief Creative Officer Geoff Johns and Gustin answered those burning questions and offered up eight things to know about Barry’s introduction.

HE’S A NICE GUY | “Barry comes to Starling City because there is an unexplained robbery at Queen Consolidated, and Barry is very interested in the unexplained, for reasons we find out over the course of these two episodes,” Kreisberg teased. “He’s the opposite of Oliver in a lot of ways — outgoing and funny, a little bit unsure of himself and smart.” The physical contrast, too, between the square-jawed vigilante and Gustin’s lanky, youthful alter ego is “both comical and fun.”

GUSTIN WOULD BE BARRY’S PAL | The Glee alum, who was the first person to read for the role, “immediately thought [Barry] was funny and endearing, and I hadn’t done anything like that,” the actor said. “He’s fun to play. He’s likable. I would be his friend. I haven’t had the opportunity to play a character that I would actually enjoy spending time with.”

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SPARKS FLY | In trying to figure out a way to introduce Barry into Arrow‘s world, the writers spent a lot of time “talking about Oliver and Felicity and their growing … feelings for each other,” Kreisberg revealed. “[Because] Barry and Felicity are so similar — they’re both a bit uncomfortable in their own skins and very likable and personable — it just seemed like they would instantly hit it off, which would just complicate things for Oliver even more. It felt like the right way to go.”

THERE WAS A CHEMISTRY TEST | And we don’t mean one performed by Barry. Emily Bett Rickards, who plays Felicity, was brought in to read with Gustin, after which “it was like a done deal,” Kreisberg related. Joked Berlanti: “We wanted to make sure he didn’t seem like jailbait next to her.”

YOUNG JUSTICE | “We’d always seen [Barry] as being a little bit younger,” allowing for a few playful jabs at the scientist’s expense to address the elephant in the room, said Kreisberg. Not being super-confident and strong, Barry “needs the bolt of lightning to be a hero in a way [Oliver] doesn’t need the bolt of lightning.” Added Johns: “[Oliver] needs the heart, Barry has the heart. [Oliver] has the body, Barry needs the body.”

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HIS FUTURE IS BRIGHT | Now that The Flash is getting its own pilot rather than a backdoor one, “Episode 20 will just be an episode of Arrow” — which has actually turned out to be a blessing, Kreisberg admitted. “[A backdoor pilot] actually made it a little bit harder because we were going to have to take a right turn [from] where we were in our ongoing story to incorporate that.” Although Barry may no longer be getting his own episode toward the end of the season, viewers will still hear “about what happened to him in the way that you’re hearing now about Star Labs on the periphery, and certainly in terms of Felicity since she has a connection with him,” revealed Berlanti.

THE DC LORE RUNS DEEP | “We’re using a lot of mythology and characters from the comics in the development of The Flash,” said Johns. For one, the tortured backstory for the character in the comics will play a big role in the pilot. “To use how he reimagined the character’s origin and to have it be so emotional and to now actually be able to render that in pilot form has been terrific,” Berlanti raved.

OTHER FLASHY HEROES | “In success, hopefully, with The Flash, there’s a way to bring on some of the more fantastical characters that will probably still go through the grounding lens with which we view everything [on Arrow],” said Kreisberg, adding that “there’s a hint of a major character in the [Flash] pilot,” but he warned that it could be cut.