- For his Earth One equivalent, see Barry Allen.
- "Do you know what we did today? We convinced her, Killer Frost, to show us the way. And we walked on footprints of ice. ICE! And all of us risked our lives, knowing Zoom was after us to rescue you and Jesse."
- —Earth Two Barry encouraging Earth One Barry[src]
After Barry Allen from Earth One watched him give a news report on Zoom, Earth Two Barry was abducted and brought back to S.T.A.R. Labs where he was initially confused at how the person, who kidnapped him looked like him before noticing Harrison Wells and becoming starstruck. During his gushing over Wells' thesis on String phenomenology, his Earth One counterpart tasered him in order to take his place and find out what the CCPD knew about Zoom's whereabouts. Barry also learned while masquerading as his Earth Two counterpart that he was married to the Iris from Earth Two, his mother was still alive and the Earth Two Barry and Joe shared a mutual dislike. When Earth One Barry told Earth Two Iris and Earth Two Barry to get somewhere safe, due to Zoom. Iris said they have a place in Atlantis to stay for the time being. It is unknown if they made it in time.
After Cisco Ramon escaped from Zoom, he and Harrison Wells realized that they have restrained Earth Two Barry for a full day. While Barry complained about being held captive, the three tried to hide from Zoom. Wells told Cisco to silence him. Fortunately, Zoom flee away. Later, he argued with his wife, Iris, since Barry wasn't there when her father passed away. She further noticed that she kissed a different person instead of her husband. After deciding to track down Killer Frost, Earth Two Barry joined with the Team Flash in order to rescue Earth One Barry and Jesse Quick. When Killer Frost was willing to help them to reach Zoom's hideout, Barry freaked out about walking atop of ice. After finding a prisoned Earth One Barry, who was unable to pass through the barrier set up on him, he encouraged Barry that he could pass through it. Earth Two Barry further told him that he's just an ordinary human, not like his counterpart, who is also a superhero, "the Flash". Thanks to his words, the Flash was ultimately able to pass through the barrier. Shortly after Zoom arrived, the team escaped from him.
Kind-hearted like his Earth One counterpart, he is a loving husband and is shown to also be a lot more geeky and insecure than his counterpart. Both, however, share the same sense of heroism as Barry proves he can be courageous by accompanying Iris, Wells, Cisco Ramon and Killer Frost on the rescue mission to save Jesse Quick and Earth-One Barry, despite the danger of being caught by Zoom. He even motivates Earth-One Barry into phasing through his holding cell when Barry tells everyone to leave, as he is unable to phase through the cell walls.
- Genius-level intellect/Expert computer skills: Just like his Earth-One counterpart, Barry has great intellect. Barry is adept with computers, as he was the only one who could write an algorithm to find Killer Frost.
- "Flash of Two Worlds" (mentioned)
- "Welcome to Earth-2"
- "Escape from Earth-2"
- "King Shark" (mentioned)
- "Trajectory" (mentioned)
- "Versus Zoom" (indirectly mentioned)
- He is a fan of the science fiction series Commander Carl: Space Marshal of the Galaxy.
- Barry is one of the few Earth Two residents who is not the opposite of his Earth One doppelgänger.
- According to the phone in Barry Allen's house, he is friends with Bruce, Hal and Diana who are the alter egos of Batman, Green Lantern and Wonder Woman in DC Comics.
- He is left-handed, as revealed in the episode "Invincible".