Phoenix Downs have been useful items in the Final Fantasy series. They are used to revive a character that has been knocked out in battle. This use has led various conversations, usually through jokes, regarding the item's potential usefulness outside of battle.
Many such memes have resurfaced following the release of Final Fantasy VII Remake. The death of Aerith Gainsborough in the original Final Fantasy VII is one of the game's most famous twists, and while the first part of FFVII Remake doesn't reach that point in the story, that hasn't stopped fans from revisiting that tragic moment. Many have joked that, if a Phoenix Down can be used to revive a character in battle, why didn't Cloud use one to revive Aerith?
Phoenix Downs have been recurring items since their introduction in Final Fantasy I & II: Dawn of Souls. Collected from the tail feathers of a phoenix, this powerful item can be used to revive downed teammates in battle. However, for as powerful of a mechanism as it can be during tough battles, outside of battle, Phoenix Downs seem to have little power.
The belief that Phoenix Downs could restore life to a dead character comes from a common misunderstanding about characters whose health bar is depleted during battle. When completely out of health, characters are considered knocked out, which is separate from dying or even being put to Sleep. Characters who are KO'd are considered unconscious or badly hurt, not dead.
Final Fantasy V was the first to showcase the limitations of healing magic and items. One of the main party members, Galuf, at one point is the only character who has not been incapacitated in a battle against the powerful boss, Exdeath. Despite his health being at zero, Galuf continues to fight. When Exdeath flees, the party tries in vain to use powerful healing spells to bring back their friend, but the wounds that he has endured are too much, and Galuf dies.
Like Aerith, Galuf suffers wounds that go beyond the capabilities of healing magic and potions. For all of their power, Phoenix Downs are not infallible, and they fall short of being able to actually resurrect characters.
Other characters also suffer such fates. Among them are FFVII's Biggs, Wedge and Jessie. Introduced at the beginning of the game, these three NPCs are integral to the success of the bombing missions. But just when the audience is starting to get to know these members of AVALANCHE, they are killed in a bombing mission when Shinra destroys Sector 7. Cloud, Tifa and Barret manage to escape, but Biggs, Wedge and Jessie perish in the fall.
Then there's Reks, a seventeen-year-old soldier in the command of Captain Basch who's playable during Final Fantasy XII's tutorial. The teen follows Captain Basch in an attack on Nalbina Fortress, staying back to give Captain Basch and his men time to reach the king. But when he finds them, the men of his troupe and the king are dead, and Reks himself is stabbed by a man he thinks is Captain Basch. As Reks drifts in and out of consciousness, succumbing to his wounds, his last thoughts are of his brother, Vaan.
There's also Vivi, whose death happens off-screen and is only alluded to in the ending sequence of Final Fantasy IX, though it is no less emotionally moving. Vivi is a prototype for a race of Black Mages created to use magic as a weapon in the coming war, and throughout the game, Vivi learns that Black Mages have a limited lifespan. Despite his clock running out, Vivi presses on in his quest to help his friends save the world. Like the other characters who sustained major wounds, no Phoenix Down could have saved Vivi.