Let’s not mistake ourselves: the title of heroine, and, subsequently, love interest, is initially granted to Aerith. Final Fantasy VII’s dating mechanics is set up so that Aerith is the person who Cloud eventually takes on a date to Golden Saucer, as evidenced when you’re awarded a whopping 10 points, the most social points the player can earn in one action, if you have her accompany you to fight Dyne in Corel Prison. Even Cait Sith’s fortune reading in the Temple of the Ancients, which says that Cloud and Aerith are perfectly compatible, leads us on to believe they are to destined for one another. Aerith’s role in the game is so incredibly powerful that, for the most part, it places Tifa in the shadows and convinces one that Aerith will be the supporting heroine to carry the game to the end.
In a surprising twist, the role of of the heroine shifts to Tifa after the death of Aerith. This is not immediately apparent in the scenes after her passing (for which the player may still be emotionally recovering from), but in the first visit to the Northern Cave when it is fully revealed that Tifa is aware that Cloud’s memories are indeed fabricated. This idea is then extended to the start of the second disc as we take control of Tifa upon Cloud’s disappearance. Though she is initially offered the role of leader in his absence, she turns the position down knowing that she herself isn’t capable, much to Barret’s disappointment. Still, we are given control of Tifa for a brief period of time before visiting Mideel. As Tifa, one can complete certain sidequests, interact with the party and NPC’s, and even play a mini-game that convinces us Tifa can hold her breath for an infinite amount of time (she’d make a formidable Blitzball player, honestly).
It is true that Tifa’s character was conceived once the the developers had decided to kill off Aerith in the early development stages, making it easy to insinuate that it renders Tifa as a somewhat inferior substitute. However, Tifa remains a stark contrast to Aerith. Tifa had her own set of motivations more in tune with her past and the people immediately around her, particularly Cloud. She finds it difficult to express her feelings, choosing to bottle them up, unlike the more outgoing Aerith. She is ultimately her own character, and turns out to be a different and unexpected kind of heroine altogether.
Perhaps the idea of Tifa as the heroine by game’s end is most exemplified by her popularity in pop culture. Even in the decades after the game’s release, Tifa Lockhart is still besting RPG heroines in public poles. Attractive looks and strong melee fighting capabilities at hand, she has accumulated a kind of renown comparable to Lara Croft and Chun-Li. Although it is difficult to ignore the hyper-sexualization by the developers and in fanwork, many fans do still recognize her as a complex character with her own story and personality.