Jin probably has it the worst. Being separated from his beloved mother at age fifteen, having trusted and been taken under the wing of his Jerkass grandfather for four years just to be betrayed by him at age nineteen, the constant battle against the Devil Gene in him, resorting to starting World War III all just to end to his cursed bloodline... What more could a player ask?
Even defeating Azazel wasn't enough to free Jin of his curse. To be truly free of the Devil Gene, he must confront the real cause of his suffering: his grandmother. Sadly Heihachi beat him to it decades ago. He has but one recourse: Kill Kazuya once and for all and find any surviving remnants of the Hachijo Clan if that's possible.
Most of Steve's endings really... in T4, he meets his mother for the first time as she saves his life, only for her to disappear again. In T6, he gives his winnings to pals Paul and Marshall, only for a bomb that was planted in the winnings blow them up. The look of horror on Steve's face pretty much says it all. Lastly, in TTT2, he has flashbacks to his days as a lab rat for the G-Corporation/Zaibatsu and Emma Kliesen, who we see was the one friendly face he had. She then leaves, and due to Leo's storyline, we know what happens to Emma. Seems like anyone who gets close to Steve isn't going to end up well.
Marshall Law's Butt-Monkey status within the series, is, if seen from a certain perspective, very sad, especially since he has a family to look after, which means that his fortune is their fortune, too. From his Perpetual Poverty, to constantly losing his dream of opening up a restaurant, and then, in T5, learning that his son, Forest, is involved in a motorcycle accident, while he himself still struggles to find job in Japan under constant fear of being deported as an illegal laborer (which comes true in T6)...
Kazuya's ending in Tekken 1 is a bit sad in hindsight. Sure, he finally got revenge on Heihachi, and the ending had a somewhat upbeat tone. But upon hindsight, that moment leads to Kazuya turning into the monster he becomes for the rest of the series.
Kazuya's downfall. Kazuya Mishima, originally kind and virtuous, thanks to his father's harsh treatment and murder attempt, was forced to make a Deal with the Devil to survive. Eventually Kazuya was slowly corrupted; but even though he seemed to be beyond redemption, he still had good in him. Jun Kazama, through her benevolent powers, was able to weaken Devil enough to make his good side resurface, thus creating the being "Angel", that wanted to free the young Mishima from the Demon's influence. This inner struggle causes Kazuya to have a morality crisis, confused as to who to support, weakening him to the point that Heihachi was able to defeat him. Then, after Heihachi throws Kazuya's body into a volcano in an attempt to kill him for good, Angel disappears. From then on, Kazuya's good side is condemned to be forever shrouded in Devil's darkness.
Baek's backstory. My. His father was formerly a taekwondo champion until an accident abruptly ended his career, which sent him into a deep depression. Baek's mother left them at around the same time, leaving Baek's father to raise his son alone while simultaneously handling his personal problems. Then, just as they were about to have some fun at one time, Baek accidentally killed his father. No wonder he went a little into the deep end afterwards.
Animated into its full glory in Baek's TTT2 ending. Here. Prepare your tissues.
Wang's ending has him visiting a grave, with him pouring a drink for himself, then pouring the rest over the grave. Come Tekken 5, we find out the grave is supposed to be for his friend, Jinpachi Mishima.
Jack 2's ending; he's out with Jane, enjoying the scenery and watching her play around when all of a sudden, a satellite shoots a beam at him, effectively destroying him. The last thing we see is Jack's POV of Jane reacting in horror as he shuts down.
King's ending; he's failed to win the tournament and can't bear to face his orphans, so he leaves presents outside for them and walks away until the children all run out to meet him. The music and the knowledge of what happens to him in between Tekken 2 and 3 is quite upsetting.
Eddy's childhood, or rather, his lack of one. Back when he still reigned as CEO, Kazuya bankrupted the Gordo family, then, through his goons, murdered Eddy's parents. Then Eddy had to live most of his young adult years behind the bars for a crime he didn't commit. Yet another innocent life screwed up by the Mishimas.
Jin's Greatest Failure: he wasn't there when his mother fought Ogre to protect him and subsequently vanished.
Consider this: Jin was a mere 15-year-old teenager when Jun went missing. He was essentially raised in the wilderness, thanks to Jun deciding to move to a quiet forest in Yakushima, a mostly uninhabited forest-laden island located off the coast of Kyushu. Then during that night, his only caregiver was taken away by what can be best described as a "natural disaster". Imagine seeing a helpless young teenager crying and screaming for his mother alone in the darkness of a forest...
Being a workaholic can be detrimental to one's social life, as described in Lei Wulong's Tekken 4 prologue. Not only were his cases unsuccessful, but losing his girlfriend in the process was the kicker to everything.
To make matters worse, his live in girlfriend dumped him for his assistant and his rivals told his superiors that he was letting personal affairs interfere with his investigations. As a result, poor Lei was suspended for a month.
Wang Jinrei's ending in Tekken 5: it's really rather sad how Wang had to destroy the Tragic Monster Jinpachi's become. as Wang turns around and sees Jinpachi, the demon screams in pain and Jinpachi reacquired briefly his consciousness, happy that his friend made it there. Wang is then shocked to see his friend changed into a monster, Jinpachi begs Wang to kill him, but Wang refuses as he doesn't want to harm his friend.As Wang walks away, Jinpachi begs to Wang to kill him because his consciousness is almost gone while Wang says "There must be another way".
Wang: (walks around the area, unware of Jinpachi behind him, and turns around)
Jinpachi: (sees Wang's face, and he screams in pain for a few seconds) My friend... I'm surprised you made it here.
Wang: (shocked) Jinpachi? What happened to you?! What caused you to turn into this?
Jinpachi: Please... my consciousness is almost gone... don't let this monster take full control. It will be the end of humanity!
Wang:There must be another way...
Their last talk together puts a lot of emphasis on the "Tragic" part. Wang sees his friend (now returned human) on the ground, and holds him in his arms — reuniting once again after 40 years. Jinpachi excuses himself with Wang for the trouble that Wang had to go for him, while Wang says that it's "nonsense" and that he and Jinpachi have been through a lot together and feels they're like brothers. To this, Jinpachi calls him and struggles to raise his hand, that is immediately held by Wang. Jinpachi then regrets to not have time for them to drink together one last time, then bids him farewell and dissolves into dust. Wang then calls to him like he's about to cry, mourning the loss of his best friend.
Wang: Jinpachi.. Jinpachi! Are you okay?
Jinpachi: I'm sorry I've caused you so much trouble.
Jinpachi: I wish we could have had one last drink together... but I'm afraid my time has come. Goodbye, my dear friend. It was fun... (disintegrates)
Wang: Jinpachi! Jinpachi... (he grips the dust, and his voice cracks as if he's about to cry) It's the curse of the Mishima bloodline! My friend... it seems my time has yet to come!
Wang is a life long friend of Jinpachi, he entered the tournament because of him wanting to see him again, and Jinpachi was the reason why Wang is the only one that sees the Mishima family in a good light, wanting for them to destroy their curse while scolding the world for being so indifferent to their plight
The most chilling part is him acknowledging that Jinpachi's death is not enough to fulfill his friend's wishes, and as he stands, he knows that he cannot follow his friend just yet.
Mood Whiplash: This ending is used for the Funny Moment of Wang's Tekken Tag 2 ending. Wang and Jinpachi also poke fun at Wang's death during the former's ending in Tekken 6. But damn if you didn't agree that Wang's "awesome existence" justified his presence in the latter games.
The only moment where Kazuya shows affection to someone —
Kazuya: Jiisan... Jiisan! (Grandpa... Grandpa!)
Jinpachi: (opens his eyes)
Kazuya: (smiles at Jinpachi) (Flashback when Kazuya was a kid sparring with his grandpa) Grandpa!
Jinpachi: Kazuya! (end flashback) Kazuya...
Kazuya's ending in Tekken 5. Kazuya rushes to his unconscious grandfather, holds him in his arms and tries to wake him up by shaking him lightly and calling him "Grandpa"(Jiiisan in the original language, that is an affectionate yet respectful term for grandfather)reuniting with him after 40 years, he grows more desperate but then Jinpachi opens his eyes, Kazuya, surprised, realizes his grandfather is still alive and overjoyed, smiles affectionately to him, then he has a brief moment of happiness as he flashback from when he was a child, sparring with his grandfather, in this moment Kazuya's humanity and good side resurfaces. Unfortunately the moment of happiness is brief as Devil takes over Kazuya, his warm smile turns into an evil smirk and his red eye glows, then Kazuya kills Jinpachi.
It's even more sad when thinking that Jinpachi was one of the few people in Kazuya's life that didn't try to harm him but genuinely loved him, acting like his fatherly figure, being one of the few happy childhood memories. Devil probably possessed Kazuya and killed Jinpachi, but also proves that Kazuya still has a good side but that's totally suppressed by the demon.
Lei's interlude with Jinpachi —
Lei Wulong: Now, tell me, what are your true intentions?
Lei Wulong: You stole the scroll from China as well!
Jinpachi: That was my son, Heihachi. I will return it now. It seems my time has come...
After defeating Jinpachi, Lei asks Jinpachi the reasons of his actions, and Jinpachi, now conscious but in pain, tells Lei of all the events, from him being betrayed and imprisoned by his own son 40 years before, enduring the painful imprisonment until dying of hunger, having his body resurrected and taken over by an evil entity that forced him against his will to execute its order to destroy the world and kill anyone in the way, and in the few moments he regained his consciousness, sending a letter to his old childhood friend, Wang Jinrei, to seek him out and organize the King of Iron Fist Tournament 5 in the hopes that someone would stop him. Shortly after, he says that his time has come, vanishing into dust after, leaving the stolen scroll on the ground. After picking it up, Lei walks away, turning around for a moment as if thinking of Jinpachi, then leaves.
During this speech, Jinpachi is clearly in significant pain — not just physical, but emotional pain that he endured from trying to bring his son to justice, only to die alone and be forced against his will to destroy the world.
To think that Jinpachi was once a good man with ideals, friends with Wang Jinrei, he led his family company with good intent and cared about his grandson Kazuya that was often mistreated by his father Heihachi, taking the role of his fatherly figure teaching him the Mishima Karate and taking care of him. After Kazuya dissapeared, Heihachi took over Jinpachi's company and Jinpachi tried to look for his lost grandson, when he discovered his fate and heard that Heihachi was about to turn the Mishima Zaibatsu in a militaristic organization, Jinpachi tried to stop Heihachi, only to fail and be imprisoned.
How did Bryan show his thanks to Dr B and the Manji Clan for saving his life? He slaughtered the clan and injured Bosconovitch. Some thanks.
Miguel's Origin Story. He was a wild man and had run away from home at the age of fifteen, yet the only family member who didn't shun him for what he did was his little sister. Years afterward, he attended his wedding, which turned into a place of chaos when a Mishima Zaibatsu airship abruptly shot the church, causing an explosion and killing Miguel's sister. Roaring Rampage of Revenge ensues. This moment is included in the game's opening, as well, complete with Miguel's Skyward Scream.
And then it turns out that the reason for the bombing is because Jin wants to spread as much hatred as possible to the world, so Azazel can be given a corporal form. Yeah, Miguel's tragic life is a mere drop to achieve a greater good. Heartbreaking.
Baek's Tekken 6 ending is enough to draw a tear from anyone. As he takes an attack from Azazel which was intended for his pupil Hwoarang, he retaliates with a large kick and puts an end to the monster, only to collapse lifelessly to the floor. Hwoarang, as the faithful student he is, rushes to check on his master and calls out to him, but gets no response and lets out an anguished scream of ''Master''note Sabeum Nim!to the sky. Poor guy...
Similarly, Wang's death in 6. Defeating Azazel, a weary old man who blames the world's current predicament on his indifference to the Mishima family and their cursed bloodline lays down to die and be reunited with his best friend Jinpachi.
In the prologue of Scenario Campaign, Jin states how much he misses his mother and his wish for them to be reunited, even if he thinks that she may be already dead somewhere. He never completely moves on from her.
Christie and Eddy get a massive Happy Ending Override moment compared to their non-canon endings from Tekken 5, where it's revealed in their endings for this game that Christie's grandpa died.
The fact that Daisuke Gōri (Heihachi's voice actor) died shortly after this game. The guy's been voicing the old man since Tekken 3. This is then followed years later by the death of his replacement, Unshō Ishizuka.
Tekken Tag Tournament 2
A relatively minor one, but if Jinpachi is paired with Kazuya, his intro has him say his grandson's name in a mournful tone of voice, as though trying to apologize for the shitstorm their family turned into.
TTT2 delivers a sad end for Christie. Looks like she'll finally forgive Eddy for his stint with the Zaibatsu in 6, except there were lots of people in the train station who dressed like him from behind and just when she found him, he didn't notice. When she's about to board his train, Christie got occupied with cheering up a crying girl, and when the deed's done, the train left. Eddy finally noticed Christie's pleas to wait, but he shook his head sadly, he probably couldn't forgive himself for doing that stint. It's a sad day for both Capoeira users.
In Jin's ending, after Unknown is defeated, Jin is holding her in his arms as she reverts back to Jun and then fades away into nothingness. After a few moments of silence, Jin angrily transforms into Devil Jin and flies off screaming in rage. Continuing into Devil Jin's ending, Jin still screams in rage as he flies into space. A spirit of Jun appears before Jin and becomes one with him. Jin falls to Earth as his Devil Gene is neutralizing and he is found unconscious on a beach.
Lars' Ending can be seen as this when you consider what's shown. Maybe the dream Lars' had was what the Mishima Family could have been if it weren't for what Heihachi did...
Combot's TTT2 ending. There's no dialogue, but instead we see Combot staggering through a city, seeing thrown away machinery, then watching cars being crushed over and over. Then, he just gives up as his arm and leg break apart, and he falls to the ground. Then he briefly awakens again, to see Violet looking over him, and just as suddenly ceases to function. The worst part is Violet seemingly crying over his robot's 'death'.
Jack-6's ending in Tag 2, reminiscent of the ending to The Iron Giant. Just as an asteroid is falling towards Earth, Jack-6 takes flight towards the asteroid and starts hammering away at it, only to have minimal effect. It looks like Jack-6 is about to fly away from it, only to fly towards it full throttle and uses all his power to break the asteroid into bits and sacrifices himself in the process.
There's also the fact that Heihachi himself does not look at all happy. During the trailer, when Kazuya confronts him with killing Kazumi...a tear actually falls down his face.
Even worse, during the trailer, there is also a carving on the wooden floor near Kazumi with an umbrella and two names underneath it. The two names are Kazumi and Heihachi. In Japanese culture, this is pretty significant as having two names carved under an umbrella is meant to signify that the couple whose names are carved there will be together forever. Makes you wonder how the relationship between Kazuya's parents had been before things had gone to shit.
And then you realize that Kazuya's name is actually a fusion of kanji between Heihachi and Kazumi. note Kazuya = 一八; Kazumi = 一美; Heihachi = 平八; take Kazumi's fist kanji, and Heihachi's last, and you get Kazuya's name in kanji.
The actual circumstances behind Kazumi's death. With her Devil Gene awakening uncontrollably and causing her to attack Heihachi randomly, not to mention foreseeing the future that would become the rest of the series due to Heihachi and Kazuya, Kazumi attempted to end her prophecy before it even began despite absolutely loathing the mere idea of trying to kill her husband. Up to this point, Heihachi had actually been a kind, loving husband and father and even tolerated previous attempts to kill him due to knowing it wasn't her fault, but Kazumi's final attempt on his life being of her own consent created a betrayal so vast that it broke him; he even hesitated to kill her despite having every reason to. After that, he would toss Kazuya off the cliff for the sake of finding out if the Devil Gene was inherent in him as well, and Kazumi's mistake would cause everything to happen in the first place. It also shows that just like how Kazuya and Jin both despise Heihachi for his Chronic Backstabbing Disorder, they're not so different and all are personally spurned into horrible acts by family betrayals twisting them.
A large, misfortunate part of this can also be attributed to Poor Communication Kills. In their confrontation, Kazumi intentionally plays up a hostile role and proclaims she only ever really married Heihachi for a chance at revenge. Heihachi was never given any reason to think otherwise besides his own personal feelings and history with her, thus believing her to be nothing more than a traitorous person that had tried to extort his feelings for the sake of vengeance, even to her last words in trying to spare her. She tried to get him to relent when she realized she couldn't beat him, but by then it was too late in his mind. And in the present day, her wayward spirit knows this.
After years of fighting Kazuya and Jin in a never-ending blood feud of betrayal and hatred that had enveloped the globe, Heihachi marches off to one last battle with Kazuya to settle the score once and for all now that both of their companies have been ruined and they have little else besides their mutual hatred. In the end, only one is left standing - and it isn't Heihachi.
Heihachi even allows the reporter framing the story to know full well what happened with Kazumi and Kazuya, his reasons for his Start of Darkness and why he became who he did, with intent on letting the world know once and for all who Heihachi Mishima really was. When the reporter is about to be carried out by guards because Heihachi knew full well of the man's cooperation with Lars and his hatred for him, the man asks him an Armor-Piercing Question about what he thinks of their ongoing war. Heihachi actually pauses and looks at him with what's described as a "mournful look in his eyes;" judging by immediately challenging Kazuya afterwards, it's entirely possible that Heihachi realized shortly before his death just how much of a bastard he'd really become and intended to go out fighting.
For a brief moment, when Kazuya found out that his mother arranged his death by the hand of Akuma, we catch a glimpse of him showing a sad emotion. For the longest time, his mother was one big reason why he hated Heihachi and his Morality Pet. Once that reveal sinks in, his world broke further: Ever since he was born, his mother wanted him dead just in case, he was all alone this time with just the Devil as his company and eventually power source. Sometimes, even Devils may nearly cry before assuring that all of it won't matter.
Normally when Kazuya prevails over his kin, he gives an evil smile or chuckles. At the end of it all, he isn't smiling now. Maybe even he has seen the futility of it all. Even more so, the music accompanying his victory was surprisingly somber instead of the usual ominous evil track accompanying Kazuya's victories.
The main menu theme, Solitude. A somber piano piece that encapsulates very well the tragedy of so many of the characters.
Not to mention the staff roll credits songs; Aloneness, a version of Solitude with lyrics sung by Kazumi's seiyuu Yumi Hara, and The Long Goodbye, a rather serene piece with some pretty heartbreaking lyrics. Watching the linked video that has segments of some of the characters' tragic backstories makes the effect even stronger.
The lyrics to both songs are even more sad when you understand what they represent. Aloneness represents Kazumi's feelings about Heihachi, telling him that she still loves him despite the monster he became and is waiting for him in the afterlife. The Long Goodbye, on the other hand, is Kazuya's feelings about Heihachi, expressing his hatred towards Heihachi for not telling him why he treated him horribly, why he killed the only two people in his life who loved him, and threw him off the cliff on that fateful day. In the end, he gave into his hate and decided that revenge was more important, but after finally getting it and killing his own father for good, he feels empty and that Heihachi is taunting him by taking the truth to his fiery grave.
In other media
Shin Kamiya of Blood Vengeance. Poor kid. He and his classmates were made guinea pigs for the Devil Gene testing by the Mishima Zaibatsu solely because they happened to enroll within their school, the Mishima Zaibatsu Polytechnic. Thanks to the test, all of Shin's classmates died, with the exception of Shin himself, who had to endure the rest of his life knowing that his life is cursed by the Gene, mentally and physically (his body is permanently marked with green tattoos). He tries to commit suicide once and twice, but can never manage it because his newfound power prevents him from dying. Then finally, when he goes on an assault to Heihachi to take revenge for what he did, Heihachi nonchalantly kills him. As he lays dying, he states to Xiaoyu that he can finally break away from the Gene's influence and attain peace, even in death.