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Tear Jerker: NieR
The equally depressing and heartwarming game know as NieR is essentially 50% genre/medium savvy humour and 50% undiluted tearjerker.
Unmarked spoilers ahead!
The Lighthouse Lady quest chain. At first, she appears to be a cranky, sickly old woman who puts Nier through hardships to pass time, but as you progress through the story, you learn why she's been living in the lighthouse for the past 50 years. In order to keep Seafront's lighthouse lit, the people of the town have been sending her forged letters from her lover, deceiving her into thinking that he was recovering from an illness in a faraway land. Eventually, Nier and Weiss catch onto the hoax and extract the truth from the postman; he reveals that the Lighthouse Lady's lover died long ago but they couldn't bear to tell her.
At this point, you are given a choice. You can either perpetuate the lie with one last forged letter from the Postman, telling her that her husband has embarked on a long journey to return and that she should wait for him at Seafront, or reveal the deception to her. If you tell her the lie, she acts overjoyed and passionately tells Nier to thank the Postman for the letter. But, if you tell her the truth...
Lighthouse Lady: You don't have to apologize. To tell you the truth, part of me had suspected something like this. But it's hard to hear a secret thought finally spoken aloud. I...I think I should be alone for a while. But I want to ask you a favor. You must forget we ever had this conversation. The entire town has worked on this story, and they did so to make me happy. I don't want their hard work to go to waste, so I shall carry on as if I am none the wiser.
Really, the quest starts getting tragic when you discover she has the Black Scrawl.
Lighthouse Lady: Oh. You. I suppose you want to tell everyone about my illness, hmm? Well, don't! I don't fear death! I've lived long enough, and I'm tired of it... And tired of being alone.
When you return to Seafront after completing that quest, you learn that the Lighthouse Lady had finally passed on.
Surprisingly enough, the Fisherman's Gambit quest chain turns into one of these. After watching Nier bond and learn from the Fisherman at Seafront, you are told once you finish the final quest by another NPC that the Fisherman died. Many gamers are surprised to learn that the Fisherman was actually an outcast in Seafront; he had been an old soldier, and the town had feared him for the actions he took in a battle long ago. The NPC who tells you this then goes on to say that the Fisherman's interactions with Nier seemed to make him happy after living alone for so long. Cue Manly Tears and/or Tender Tears.
Resident: Oh, the old fisherman? Didn't you hear? He passed away just this morning. I guess that old war injury finally got the best of him. From what I understand, the guy used to be quite the mercenary. He supposedly did all kinds of terrible things back in his day. So truth be told, no one in town much cared for him. But he sure seemed to enjoy your company. I think you made his last days some happy ones.
The sidequest that you do to find an old man's dog. His dog would go find leaves to help his master's medical problems and numb his pain, but he disappeared one day. So you go to a bridge in the Northern Plains, where you find the dog dead, holding the special leaves in his mouth. Shades appear and it was apparent that they killed the dog. You kick some Shade ass, and bring the leaves back to tell the old man what happened... Only, when you arrive, there is a young man there instead. You're told that the old man had passed away that morning, waiting for his faithful companion to come back.
Emil's backstory. He and his sister were first used for horrific experiments, and he was forced to watch her turn into a monster. He then had to live apart from people for well over 1000 years due to his powers. When Halua was defeated and he got rid of his petrification powers, he was turned into a skeleton. However, the way that Nier and Kainé accept him despite this is also touching.
Nier: Welcome back, Emil. You've been through a lot.
Emil: But my... my body...
Nier: Yeah, I know. [they embrace]
If there's one thing Emil is deathly afraid of, it's losing his friends, as shown in the sheer desperation in his post-Kainé boss dialogue:
Emil: We're always going to be together, Kainé. If you transform again, we'll just stop it again! As many times as it takes! I don't care how tough it is, we're gonna get you back! I like being outside because I'm with you, Kainé. I'm able to ignore my appearance and keep going because of you. I'm weak, and sad, and lonely, but somehow you make me strong! You're my friend, and I need you! So you can't go away!
And then there's his Heroic Sacrifice to save the party. As if the final goodbyes weren't bad enough, when the others are gone Emil drops his brave face and breaks down, thinking how much he wants to see them again and how he's terrified of dying. That was truly heartbreaking to watch, because no matter how heroic a sacrifice is, you're still staring death in the face.
Emil: I... I want to see you again. I wanna see all of you again... Just one more time... I'm... scared. I don't want to... die...
The Ending B post-credits sequence, where Emil's disembodied head survives the explosion, lands in the desert and cheerily bounces/rolls off to find some legs and then see his friends again, only serves to twist the knife even further since he'll only be able to see either Nier or Kainé, depending on which ending you choose to go with. At least in the former case, when he finally gets back he'll never have realized Nier existed in the first place! That's...not much of an improvement...
Kainé's backstory. All of it. From being abandoned, to being ostracised, to her grandmother, to Tyrann, to being ostracised even more...
She was happy to die as soon as she avenged her grandmother, but Nier accepted her and convinced her to live, while she in turn gave hope to Emil. She sacrifices herself and is petrified to save her new friends, but thankfully wakes up again and finds them all there, if a little different to how she remembered. Then her hometown of the Aerie is wiped out, she loses Emil whom she had protected and loved like a brother, and to top it all off her inner-Shade is seriously threatening to take over her mind and force her to kill the man she loves. Depending on which ending you get, she either dies at Nier's hand and is allowed to finally rest, or is cured and able to live on in peace with a rebuilt Emil, at the cost of completely forgetting about Nier. In other words, no matter which path you chose for Kainé her life will always be tragic.
While getting ready to "avenge" Jakob. You slowly find out that the abandoned child Shade Kalil befriends a robot that after learning what "crying" is and finding out that both their parents (creator in p-33's case) died, which gives the robot emotions to the point where it's sole mission now is to protect Kalil. Later you find out that they were teaching each other about what they knew. Interested in the outside, both the Shade and p-33 decided to leave the junk yard to explore the wonders of the world as friends. Once you face them to fight with Nier being oblivious as always, the robot grows wings and flies to the ceiling of the building in an attempt to escape the fight and protect Kalil and itself from death.
P-33: Beepy... alone... Beepy... cry?
On your second visit to the Lost Shrine in playthrough B, you see how Gretel has been coping with Hansel's death in the very first (actual) boss fight of the game. He's been sitting in that same room, focusing on how he failed in his task to protect Grimoire Weiss and how he failed to protect his brother. As you progress through the shrine, Gretel begins bonding with several small, regressed Shades, finding a new purpose in protecting his friends. And then you show up and slaughter them all. You really start to feel sorry when Gretel is screaming at his body to move right before he dies, desperately wanting to save his newfound friends.
And that's when you realize without a doubt that every single boss you face in the second half are all Tragic Monsters.
Gretel: Move... Move... Come on, you stupid arm, move! We are incomplete. But our friends make us whole! We are mocked, abused, and hated. But our friends keep us strong! That is what keeps us going! Do not stand in the way of our lives! Those... are... my friends! Come on, move!
After the first playthrough it's revealed that before he became a Shade, Roc had an owner who grew old and died, but told the wolf to keep living so he could remember him. Through Roc's memories we realise that he wanted the killing to end and was only trying to help his pack survive to keep his promise with his master.
Fyra being attacked by wolves on her wedding day provides a shocking Mood Whiplash. One minute it's a happy celebration, the next she's lying covered in blood in her husband's arms while he begs her not to die. The King's tearful speech at her grave afterwards, about how hard her life had been and how close she had come to knowing happiness, is made worse when he has to ask Nier and co. to leave him alone, since a ruler can't show weakness.
When the King and his warriors stay behind to buy time for Nier's group in the Shadowlord's Castle. After they're gone it shows the King (who is still a kid for crying out loud!) trembling but still trying to stay calm in front of the others, then asking the advisor how many rules there are about what battle cry to use before dying.
The King finally bleeding to death, surrounded by the bodies of his warriors, and promising Fyra that they will be together again.
Grimoire Weiss being zapped and permanently damaged by the Twins, to the point that he can barely keep himself afloat during the confrontation with the Shadowlord. Especially when he goes and pins down the Shadowlord at the cost of his own physical existence, finally admitting that he has grown fond of being called just "Weiss."
Now I know why the two of us were born together. For beings without souls... living alone... that would just be too sad...
Grimoire Weiss: Those two have watched the world wither for time immemorial. The cruelness of such a fate is difficult to imagine.
The Shadowlord and his Yonah have two scenes that are both heartwarming and tear-worthy. In the first ending, the final shot is of them together, with Yonah pulling playfully on his arm. The second has the Shadowlord sitting alone remembering his former life and regretting his failure to protect Yonah, before she suddenly appears at his side looking like she did in the prologue and gives him his half of the cookie, thanking him for always being there for her.
Watching the Shadowlord react... poorly to his Yonah's sacrifice is pretty heart-rending. Coming back for Ending B kicks it Up to Eleven, of course.
Shadowlord: Yonah...I cannot live...in a world without you...
The ending credits, by which time you are probably already inconsolable, is set to "Ashes of Dreams", a tragically beautiful song that pretty much sums up the plot and will provide you with no comfort whatsoever.
In the third ending, where Nier is forced to kill Kainé before she turns completely into a Shade. With the woman he loves impaled on his sword, gazing up at him, Nier gives her one Last Kiss before she fades away. Afterwards, Tyrann relays her final thoughts: "thank you".
Nier: Kainé... let's go home together.
And in the final ending, where Nier gives up his own life in order to save Kainé and bring her back. This means that neither Kainé, nor Yonah, nor anyone can remember he ever existed. After all he went through trying to rescue her, Yonah believes that it must have been Kainé. And Kainé starts crying after finding the flower Nier gave her, because she knows it's special but can't remember why.
After the final ending, when Nier has sacrificed his entire existence to save Kainé, seeing all the pages of your menu interface (as if "printed" on Grimoire Weiss,) containing all your accomplishments, your experiences, erase into nothingness one by one. Then the save files themselves are deleted. ... and the final Player Punch: upon returning to the title screen, a Lunar Tear appears next to the title.