Dolores: AI. Artificial intelligence, but in Japanese it means "Love"...
The first game has a bad ending that's really hard to achieve by normal means unless you go out of your way to do so, but definitely qualifies as a Tear Jerker nonetheless. Fail all the SOS missions, and Thunderheart will be brutally and abruptly killed by an explosion as he's talking to Leo. ADA will confirm that what caused the explosion was Jehuty destroying the colony shaft; in doing so, it hit one of the colony's underground lifelines. Cut to a grim The End screen, with a destroyed city in the background, and the game returning to the title screen. ADA's Brutal Honesty and Leo's reaction set the deal, as ADA doesn't just sound like she's berating Leo; she also sounds like she's berating you, the player, for screwing up this badly, if not outright going out of your way to cause this.
ADA: In other words, you killed him.
Leo: But, I didn't mean... *cut to the The End screen*
The aftermath of the final fight against Viola in the first game:Leo manages to win, but one of the mines set up by Viola explodes right next to her Orbital Frame, launching it outside the station, only for it be caught and dragged by Jupiter's gravitational pull. Leo asks ADA for a way to rescue Viola, but Viola herself interrupts him over the radio channel...and what follows is an absolutely heartbreaking sequence set to a haunting piano piece, in which Viola slowly breaks down as she burns up in re-entry, starting by chastising Leo for his naiveness and selfless nature in trying to save her...as she makes it clear that if he does, she will kill him and everyone he loves, and will continue killing after that. As she is slowly dragged to an horrible death, Viola opens up and rages about how incomprehensible it is that Leo triumphed over her, as she acknowledges just how opposite their very natures are, and how she was slowly turned by war into the monster she is, all while she lost the man she loved, her teammates and even her own nature as a woman to conflict, always surviving because of her talent and strength, the only things she had left as a human being, only to, after all this time, her defeat so she can fall in the battlefield. As a final wish, she asks Leo if she was strong, to which he replies he still finds it hard to believe he is still alive after their battle, to which Viola, for the first time in the whole game, chuckles and thanks him for. And to finally hammer the point of Viola being just another victim of conflict and war, she suddenly remembers Radium and his love of the stars, just as her orbital frame disintegrates and she dies, finally at peace with herself, making her defeat and death absolutely heartbreaking, all by humanizing what had been an absolutely monstrous villain through the whole game in just one single, astonishing sequence.