This season is about Barry and Iris dealing with their Kid from the Future, Nora Allen. They also have to deal with the metahuman-hating Cicada.
Tropes that apply to this season:
- Arc Words: "The timeline is malleable."
- Batman Gambit: The whole schraping season is one courtesy of Eobard Thawne, all so he could escape his execution at Iron Heights.
- Beyond Redemption: Thawne's actions in this season make it clear to everyone in Team Flash, especially his ex-pupil Nora, that there is no hope of redemption for him.
- Big Bad Ensemble: Cicada, a.k.a. Orlin Dwyer, later Future Grace Gibbons, a Serial Killer who Team Flash must catch, and Eobard Thawne, who carefully manipulates the events of the season to ensure his own release while also causing Barry’s family no end of mental anguish. Eventually, the latter wins out in the end.
- Central Theme: This season deals with the theme of legacy in general, and the legacy of the Flash family in particular.
- The Dark Side: The Negative Speed Force from the comics is formally introduced to the show. It's channeled by negative emotions and leeches positive energy from the Speed Force and is primarily colored red.
- Evil Counterpart:
- Cicada to the Flash, since they're both motivated to do right by their loved ones. This becomes more pronounced when Cicada II - a.k.a. Grace Gibbons comes to the present to stop Team Flash from curing her uncle and then her kid self.
- Grace Gibbons is one to Nora. Both are from the future, very immature, but Nora got over her anger, whereas Grace Gibbons let hers consume her.
- Future Imperfect: Nora spent her childhood visiting the Flash Museum and soaking up the exhibits which gave her an idolized picture of her dad. Much to her repeated frustrations the more time she spends with her parents the more she learns that the museum got many, many things wrong.
- The Heavy: Orlin Dwyer spends most of the season as Cicada, hunts down metahumans that must be protected, unwittingly inspires his niece to follow in his footsteps and become an even greater threat, and is indirectly responsible for imprisoning Eobard Thawne, who manipulates Nora.
- Kid from the Future:
- Nora, all the way.
- Cicada II — Grace Gibbons.
- Left Hanging: It's never explained how Iron Heights came in possession of Cicada's dagger and put it in Thawne's chest, let alone does the show explain why Thawne traveled to the year 2034 in the first place.
- Supernaturally Young Parent: Nora West-Allen travels back in time to meet her father. Since Barry's current time period is before her birth, Barry and Iris look absurdly young to have an adult daughter. This stands out particularly because Nora is supposed to be in her late 20s, making her only a few years younger than Barry and Iris who are both 30 years old. In real life, Jessica Parker Kennedy (Nora West-Allen) is 5 years older than Grant Gustin (Barry Allen) and 3 years older than Candice Patton (Iris West-Allen).
- Super Weapon, Average Joe: This season introduces the concept of meta-tech, artifacts infused with dark matter that allows otherwise normal people to use metahuman like abilities.
- This Is Unforgivable!: Comes up a few times in the tail end of the season.
- Barry adamantly refuses to forgive Nora for continuing to see Thawne after she learned about who he was.
- Iris has this attitude towards Barry exiling Nora without her input, and reconciliation takes a while.
- Nora is corrupted by the Negative Speed Force as a result of what Barry did to her.
- Despite his initial attempt to do so in Season 2, it's made clear by Barry's actions towards Nora that he will never forgive Thawne for killing his mother and ruining his life.
- Womanchild: Played for Drama in the case of Nora, who had a rather sheltered life before major revelations.
