Aerith's death was related to the death of a real person: Sakaguchi's mother, who died early in the production of Final Fantasy VII. This made Sakaguchi, the man behind the entire series, include a realistic death in the game as opposed to the Hollywood-style deaths in earlier Final Fantasy games.
What seems to really get this scene for people, even ten years after the game came out, at a point where everyone in the known world with an internet connection knows it's going to happen, is that it's just so dragged out and emphasized. A ton of people have seen the clip of Aerith getting stabbed, but what the billions of countdowns and the like that show it fail to mention is when Cloud has to fight against his own programming to stop himself from killing Aerith, how he cradles her in his arms and insists that his feelings matter too in the face of a completely sociopathic villain, her theme punctuating the boss fight, the other party members reactions, and of course Cloud letting her sink away into the water. It all lasts for a good ten minutes to the point where even when you know full well it's coming, it still punches you in the gut with how uncompromising it is that she is dead... and that bastard deserves hell for killing her.
The rest of the party’s reactions to the scene are also individual tear jerkers:
Even though they both had romantic interest in Cloud, Aerith had become Tifa's closest friend along the journey. So when she's dead, Tifa pays her respects by kneeling in front of the dead Aerith and caressing her face gently. Then she starts to sob, and then just stands up and runs out of the area crying her eyes out. It takes a lot to make Tifa cry, and this event managed to hit her hard... She never hated Aerith, rabid bashers!
Barret, basically being Cloud's best mate for the course of the game, walks up to Aerith's body, looks for a second, and then simply places his hand on Cloud's shoulder. Having lost the woman he loved as well, Barret's comforting reaction was very appropriate for that scene.
Red XIII's mournful howl and Cait Sith's half-hearted attempts to cheer Cloud up.
But for many people, Yuffie of all people has a reaction that's perhaps the most gut-wrenching. This being the selfish little ninja who wrecked havoc on your party for no reason other than greed... but once faced with Aerith's death you can see her struggling to maintain control of herself. But then she completely loses it and flings herself at Cloud crying. And Cloud just hangs onto her and lets her cry. And even when she leaves, her sprite is shaking to show she's still crying. It makes the scene afterward, when she basically bitch-slaps Cloud and tells him he's not going after Sephiroth alone because of course they're all coming along, all the sweeter. It was this moment that convinced many doubters that Yuffie actually had a heart after all.
While the whole FMV of Aerith's death was sad, it was specifically the shot of her sinking slowly into the water and disappearing from view that turned on the major waterworks. Who cares that it's Faux Symbolism? That only adds to the sorrow.
The fact that in the boss battle right after that scene, Jenova's music is replaced by Aerith's sad, slow theme will rip your heart out, even if you knew all this was coming.
Word of God says that Cait Sith's sacrifice was so blatantly played up, only to be deflated in mere seconds, intentionally to desensitize players to dying characters, making the player believe that this is a game in which nobody dies. The next scene is Aerith's going to you-know-where. Well played, Squaresoft, well played.
Even though Cait Sith pretty much ended up being Not Quite Dead, Cait Sith's prior Heroic Sacrifice was still very touching... particularly when the moogle tripped and Cait Sith fell on the floor, then turned to the camera and made that adorably cute shrug. "Even I can save the world!" Some people - even ones who are actually ambivalent about Aerith, start crying at this one even if they know the circumstances. The music "Words Drowned by Fireworks' and the moment when he swings his arms cheerfully, then stops and slumps over for a second really make it... Jeez, darn you, Square, because that was Alas, Poor Scrappy at its finest and could be considered Rescued from the Scrappy Heap. You find yourself agreeing with what he said: another Cait Sith body may (and does) come along, but there's only one of this Cait Sith... and you're actually going to miss him.
Then there’s the part when Cait Sith tells Aerith that her and Cloud were perfect for each other. It is made even worse if you have Tifa in the party – when Cait Sith mentions that he doesn't want to say the fortune in front of the clearly distressed Tifa, Aerith encourages him to, replying, "Oh don't worry, I don't mind!"
But to a number of people, the infamous death of Aerith's actually ‘‘pales’’ in comparison to the scene where Tifa finally finds Cloud, after he fell into the Lifestream. "Great!" we all think, "He's in this town! ... In a hospital... Wheelchair bound... Nodding his head in a comatose state... completely unresponsive". It’s so despairingly similar to finding someone you know and deeply care about in a coma – you know they’re alive, but can’t do anything for them. Just imagine someone you grew up with your whole life and shared lots of happy moments together being effectively brain dead… Tifa is so broken up about it, she leaves the party to watch over him, and Cid must then take over as party leader. And you play through that scenario, so the game's telling you that it's not joking around.
The moment Cloud rejoins the party can have you crying really hard – either tears of joy because Cloud's back, really back, as he has just gotten past his identity crisis, or tears of despair, because we've just been shown what a terrible childhood he had. Either way... Wow.
The scene with Cloud in a coma is something more of us could actually imagine happening to us than Aerith's death. And while Cloud recovers later, considering this scene comes fairly soon after Aerith's death (which is itself a huge shock for any oblivious newcomer), a new player might well assume Cloud isn't gonna get better either.
The whole scene of Cloud's past. Having no friends as a kid, getting blamed for Tifa getting hurt... definite Tear Jerker.
Cloud's epic Heroic BSOD at the Northern Crater. At this point, he's pretty much hits rock bottom. He's a puppet. He doesn't have a real past. All his drives and goals were just manipulations (at least he thought that). He failed to save the Planet (by that point). He failed to save Aerith. He actually failed to become a first class SOLDIER. Now his begging to at least be numbered, to be recognized as anything, that he begs Hojo to give him a number... and Hojo tells him he's a failure even as a puppet... Ouch! Hell, forget rock bottom - he was so down and depressed he was underground.
After being tormented and mind-screwed by Sephiroth since the start of the game, he still turns to Tifa and sadly tells her "I hope you find the real Cloud". Made worse by the fact that Tifa, the only one who could snap him out of it, had been rendered mute by Sephiroth for the moment.
If you already knew about Zack (or were playing the game through again), meeting Zack's parents in Gongaga. They wonder why Zack hasn't written to them, not knowing that he's dead.
It gets worse when you play Crisis Core: you know Zack's going to die, and you know his parents have no idea what happened to him. Oh, what's that? Zack just arrived in his hometown?
The moment where Nanaki learns the truth about his father, Seto. Like with Aerith's death, the music here, the light piano reprise of the Cosmo Canyon theme, really helps drive it home.
The same music plays again...when you have Red XIII visit Bugenhagen on his death bed.
Another, though much more low-key, tearing up moment is when after Bugenhagen clearly dies, Nanaki/Red XIII comes out to rejoin the others. Something about the cliche euphemisms (he'd left, gone on a journey, was tired and had to rest) seemed much more poignant coming from the well-spoken, rather innocent beast.
When Nanaki starts referring to himself as "Nanaki, son of Seto!" He just says it with such pride...
On top of everything else mentioned here, the description text for the Seraph Comb you receive after this, "Memento of father", can make you tear up. And when the Fridge Horror sets in, and you realize that even though he's paralyzed in stone, Seto is left alive like that forever, never able to go home and be with his son...
Dyne. This is an utterly broken man driven past the point of no return, convinced that everyone he knew and loved was dead because of his best friend, driven so insane that he wants that to be the case, to the point that he planned to kill his own daughter, then when sense is finally beaten into him, he knows that mania is just around the corner once more, throws himself to his death rather than risk the life of that same girl.
"Don't ever...make Marlene cry."
Barret's complete breakdown after the Sector 7 plate collapses and crushes everything under it should receive a small mention especially since Biggs, Wedge and Jessie - all who were likable characters with good personalities up until then - got killed in that situation.
Speaking of said breakdown, just watch the scene of him shouting hopelessly at the wreckage... That kind of body language only became possible (or, rather, memory-practical) when they made the switch to polygons, but this moment showed just how powerful it could be.
Speaking of the Sector 7 plate collapse, there's also watching the plate start to fall...from the point of view of the people looking up in horror; a TV broadcast from inside Sector 7 is abruptly cut off; and then we pan out from the horrific devastation until we see it from the point of view of President Shinra, who orchestrated the mass murder and is watching it while listening to some mellow opera. Repugnant scumbag.
Elmyra waiting for her husband to return, and finally finding out from Aerith that he died on the way back from the war. Later, Cait Sith mentioning that he (as Reeve) told her of Aerith's death, and that Elmyra, along with Marlene, naturally didn't take it well.
What makes this unsettling worse was this troper actually was curious if she ever found out and headed to her home after it happened. Elmyra is nowhere to be found and absolutely no mention of her is made again.....is that supposed toimply something?
Thankfully, no. When the party leaves Midgar, way back on disk one, Barret says he's leaving Marlene with Elmyra and they are going to Kalm for safety. Marlene is later seen in Kalm in the very last FMV of the game. So although we don't see Elmyra in that FMV, and we never see either of them in Kalm itself, that is where Elmyra was when Reeve gave her the news and that is why she isn't at her house in Midgar.
Just about everything pertaining to Vincent, and let’s look at the facts. First, he falls in love with a woman who doesn't return his affections, but instead shacks up with a mad scientist. Instead of holding it against either of them, he states "As long as she's happy...I don't mind". When she becomes very unhappy very fast (see: knocked up with baby, which she has injected with alien cells but comes to regret later on), he does his best to avenge her, but is shot (and possibly killed, depending on what fanon you hold to). He's further subjected to an untold number of horrific experiments for an untold amount of time, and is cursed to transform into hideous creatures the moment his health get low, so he can't even put himself out of his misery. Once Hojo gets bored with him, he locks him in a coffin for thirty years, the entire time spent unaging, unchanging, trapped in a perpetual nightmare state, until AVALANCHE frees him (and even THAT depends on the player's ingenuity/walkthrough). And the kicker? He believes he deserves it all. Put the icing on the cake by showing him his lover insane, encased in crystal, and still not caring he's alive, and it's no wonder he out-Woobies even Cloud.
Adding to that is Lucrecia's backstory. And you can find her, all alone, in that cavern - desperately wanting to die. She doesn't even know what became of Sephiroth, her son, and deeply regrets what she did to him. When she asks whether he's still alive, Vincent chooses to spare her the knowledge of what he became by claiming that he's dead. And if you return to the cave at a later stage... she's gone. Hopefully, her soul finally rests in peace.
Before you even get to the inevitable foregone conclusion in Crisis Core, Angeal's death and Aerith's subsequent comforting of the sobbing Zack is sure to send tears spiraling down your face.
Zack's final fight in Crisis Core that leads to his death. What's worst is that they use the initially normal-seeming interface of the Limit Break system to frame those soundbites, so the first time it happens, it can catch you unaware... but then instead of the usual clear but unvoiceacted mini-cutscenes that sometimes pop up, you get staticky video with likewise staticky voices, and the pictures on the reels start to dissolve. By the end, the only face remaining is Aerith's, jittering brokenly on the reels. Considering it's implied throughout the game that Zack's Limits are activated and strengthened by his thoughts of his friends and loved ones... yeah. Just. Yeah.
Made worse by the fact that since Cloud pretends to be Zack to cope with his death, and Aerith dies before he's healed, he never got the chance to tell her Zack's dying words.
Cloud screaming in despair when the first thing he sees after breaking out of his catatonia is his first real friend dying. He then says, "Goodnight, Zack." and walks away in misery. The ending is depressing as hell.
Especially if you consider what he says before that, "I won't forget," when you consider that he did.
The scene in Shinra Manor when Vincent sees a projection of Lucrecia and the first thing he does is try to hug her. Then she walks straight through him.
"And remember... I'll always... Love you." *DEAD*
Nero and Weiss becoming one at the end of the game.
Nero: Let us become one. Let us come together, so that no one may ever tear us apart.
Kadaj's death scene in Advent Children:
Aerith: Kadaj... Stop working so hard.
Kadaj: Mother... is that you?
Aerith: Let's go back with everyone.
Kadaj then says "okay" and his voice and expression is just so innocent looking that it's hard to believe this is the same psycho bastard who's been abducting children and antagonizing the good guys this whole film.
Kadaj's death. First, Cloud catches Kadaj when he collapses; second, Kadaj still calls Cloud "brother" in that heartwrenching manner; third, Aerith comforting Kadaj (damn, Maaya Sakamoto did a good job), he thinks that it's his "mother"; and last but not least, Aerith telling Kadaj they will go back together, and we see him smile and cry out of happiness. And of course, having Nobuo Uematsu as music director, with the Awesome Music (or sad music) "The PromisedLand".
When Cloud catches Kadaj and shows such vivid compassion for him — this despite being a totally shutdown hero and so expressionless as to be almost a Heroic Mime. It's not only that Kadaj's death is suddenly – and unexpectedly – very sad, but also that Cloud suddenly shows enormous depth of character and as a character. His heroism is earned once and for all, and all the emo is swept aside, because he fights without malice or vengeance, and shows pity for the defeated foe. Not just pity, but sympathy—because he knows exactly what it feels like to be a puppet for someone else's agenda. It's that combo of heroic prowess and heroic insight (compassion) that brings about the classic catharsis. And all that is captured in one strange, small moment, when Kadaj dies in his arms.
Sephiroth. In Crisis Core, you really see how much of a good person he once was. He truly cared for his few friends. Watching that, and knowing what he becomes, is painful. Then he tells Zack "After this mission, I'm leaving Shinra," (because he doesn't want to hunt his friends anymore) and then we find out that this mission is to Nibelheim? God. Also, every single scene with Zack and Aerith in Crisis Core, considering you know it’s all doomed...
"Which is it... a memory or us?" Most of Tifa's conversations with Cloud, and her fear that he might choose death over their life together.