- “When we were kids, I loved you before I even knew what the word "love" meant.”
- —Barry to Iris.
Barry Allen and Iris West have been best friends since they were children, and Barry has been harboring romantic feelings for her since he can remember. After his mother Nora is murdered and his father Henry is arrested, Barry goes to live with Iris and her father Joe. Barry insists that his father is innocent and a "man in yellow" is responsible for his mother's death, and Iris is the only one who believes him. However, he keeps his feelings for her hidden until he is struck by the particle accelerator and falls into a 9-month coma.
Once he's woken up, he finds himself imbued with speed powers and another secret he must keep from Iris. Meanwhile, she has started dating Detective Eddie Thawne in Barry's absence, making Barry feel like he's lost his chance with her. Despite having a boyfriend, Iris remains invested in her best friend's well-being. Upon catching wind of a mysterious being who speeds around Central City saving people and stopping criminals, Iris begins documenting his exploits on her blog in an effort to prove that Barry was right about the night his mother died. Barry, on the other hand, has been tasked with keeping Iris away from danger by erasing her curiosity about "the Streak."
Of course, Barry can't help himself and starts visiting her in disguise instead, flirting with her in ways he can't when he's just himself. Iris gives him the name The Flash on her blog and ends up helping him a few times before a rage-inspiring metahuman in episode 8 (Rainbow Raider) leads to The Flash attacking her boyfriend Eddie. After that, she cuts off contact with the superhero for a time.
Iris agrees to move in with Eddie, which causes Barry to confess his love for her. Iris is loyal, however, and cannot reciprocate anymore. That is until episode 15, when her father is kidnapped and a tidal wave is threatening to destroy Central City. Iris tells Barry she can't stop thinking about him, and he kisses her before revealing himself as The Flash. Unfortunately, he immediately travels back in time in his attempt to save the city, thus erasing Iris' confession. Despite this setback, Barry still learns in episode 20 that he and Iris are marrried in the future.
When Reverse Flash (Eobard Thawne, the man who killed Barry's mother) kidnaps Eddie, The Flash comes to prevent him from hurting Iris. Sparks fly when The Flash touches Iris' hand, the same sparks that flew when she touched Barry while he was in his coma. Iris confronts her best friend and eventually her father about their lies before officially joining the team to help find Eddie and stop the Reverse Flash. At this time, Iris admits to Barry once more that she has feelings for him, but her priority is her current romantic relationship.
After Reverse Flash is caught, Barry makes a deal with him to go back in time and save his mother in exchange for granting Eobard his freedom. Iris supports this decision because she wants Barry to be happy, even though it will mean her current reality is erased. At the last second, though, Barry decides to simply say goodbye to his mother and go stop Reverse Flash. The battle does not go his way until Eddie kills himself, which essentially kills Eobard as well because he is Eddie's descendant.
Eobard's death opened a wormhole in Central City, which weakened the barrier between this Earth and the neighboring one, Earth-2. Believing himself to be the cause for Eddie's (and Ronnie's) death as well as the new villains, Barry does not renew his confessions to Iris. Instead he keeps to himself and dissolves Team Flash until Iris convinces him to come to Flash Day. After that, she recruits Cisco and Stein to return to STAR Labs and work with Barry whether he wants it or not.
Barry and Iris remain best friends but neither one brings up their feelings from the year before. Once he's fallen back into a routine, Barry starts dating a cop named Patty Spivot after some prodding from Joe, who says he must try to move on from Iris even if he'll never feel the same way about another woman. Iris is supportive of the relationship and suggests that he tell Patty he's The Flash if he's serious about her, to avoid the misunderstanding and hurt that Iris herself experienced previously. Barry does not seem ready to tell Patty, however, and instead lets her leave town without admitting it himself.
On a trip to Earth-2 to rescue Harrison Wells' daughter Jesse from the new big bad Zoom, Barry runs into Iris' doppelganger. She is a police detective who is married to Barry's doppelganger, and Barry starts playing along instead of continuing his mission because - again - he can't help himself. Eventually he and his team rescue Jesse with Earth-2 Iris and Barry's help, and Barry returns home remembering just how much he loves his own Iris again.
Despite being coerced into revealing their married status on another Earth, Barry still does not take steps towards asking Earth-1 Iris out. Instead, he helps her move on from grieving Eddie by presenting her with a birthday message from him. Barry tells her that he filmed Eddie the year before when he was preparing a surprise birthday gift for Iris, but in reality he had made sure to get some closure for Iris in his most recent trip back in time.
As far as Barry knows, Iris will use this closure to start dating Scott Evans. But Iris can't bring herself to go out with him, having decided that Barry is the man she wants to move on with. She finally tells him in episode 20, while he's deciding whether or not to undergo a risky electrocution to gain his powers back. She wants him to know that she loves him whether he's The Flash or just Barry Allen, and in the end Barry decides he has to try anyway. The explosion sends him into the speedforce, but Iris is able to get him out with Cisco's help.
His trip to and from the speedforce has Barry feeling pretty invincible, so he asks Iris out in episode 22. Of course, Zoom immediately proceeds to murder his father Henry, because Barry is not allowed happiness. After defeating Zoom, Barry still feels totally empty. Iris reminds him that she loves him and is ready to move forward whenever he is, and he lets her know that he needs time. After she assures him that she will wait as long as it takes, Barry decides to go all the way back in time and save his mother... What he feels he should have done at the end of season one.
After saving his mother, Barry enters a new version of reality in which he is not The Flash. Because he and Iris did not interact after elementary school in this reality, he works up the courage to flirt with her at Jitters and scores a date on the first try. Reverse Flash - whom he has pulled out of the time stream and kept trapped since rescuing his mother - informs Barry that soon he will lose his own powers and forget about the previous timeline entirely, which at first Barry is fine with. As far as he's concerned, it's the perfect world. However, Joe is an alcoholic who hasn't spoken to his kids in years here, and Iris' brother Wally makes for a very reckless and unsupervised Kid Flash. Once Wally is attacked by The Rival and at death's door, Barry makes the choice to return to his own reality before it's too late.
Barry thinks he's set everything right once he reappears in the show's original continuity, but it turns out there are several differences. At first the team is very upset with him, but Iris reminds them that they're a family and they have to forgive each other whenever possible. Despite his missteps, he manages to pick up where he left off with Iris and starts dating her. He discovers that the newspaper from the future that once told him he would marry her no longer says Iris West-Allen, but he does not dwell on it.
One of the big changes from Flashpoint - the name of Barry's alternate reality in the premiere - is the new big
bad, Savitar. In episode 9, Barry is propelled to the future while throwing Savitar in the speedforce. He sees himself standing in front of a freed Savitar, who kills Iris while Barry is unable to stop him. Believing he still has time to save her, Barry returns to the present and moves in with Iris without telling her what he saw.
Iris quickly catches onto his nightmares, though, and Barry eventually breaks down and tells her about her possible death. Iris insists that they need the help of the entire team to stop Savitar, but isn't ready to break the news to her father yet. Cisco uses his Vibe powers to periodically help Barry check in on the future, and Barry begins training Wally in earnest to save Iris if he himself fails. Iris goes through periods of fear and dismissal, but tells her father the truth in episode 12. Though they are cautious and stressed about Savitar's eventual return, Barry and Iris are very happy together.
Westallen is the primary canon ship for Barry and for the show, and it is also very popular among the fanbase. The fandom has grown as the show continues, helped by the fact that both Candice Patton and Grant Gustin have been vocal about the ship's importance.
Since Barry and Iris are the head of the Flash Family in the comics, there are often headcanons involving who will play their children (Don and Dawn) and grandchildren (Bart and Jenni), as well as what adventures they will get up to in future seasons of the show.
Nora West-Allen is a meta-human speedster time traveler, as well as the daughter of Barry Allen and Iris West from the future.