The story of Joe, a Ewing's Sarcoma patient who was invited to tour Riot through the Make-a-Wish Foundation. Riot then put Joe's favorite skin, Jaximus, on sale, with all proceeds going to Make-a-Wish. When Joe passed away, Jaximus got a unique new line. "Here's to you, kid!"
As a side note: Jaximus was almost put into the Legacy vault (basically, it could only be purchased whenever the vault opened), which lead to fans asking Riot not to put it into the vault. So, not only did Riot not put the skin in the vault, Jaximus is always registered as "Limited Availability" as a way to get people to look into the skin's origin and history.
Riot artist IronStylus was tasked with designing a female tank champion. He needed a strong woman to base her on... so he asked his wife to be the model. He later admitted Leona's default art is more or less an unaltered portrait of his wife, just with her hair and eyes colored orange.
Trials of the Poro, a short movie about one of the game's mascot Ridiculously Cute Critters getting caught up in a huge battle somewhere in Freljord while searching for Poro Snax. The heartwarming comes in when the terrified little poro is saved from an enormous Rain of Arrows by a huge, cheerful, bald warrior with a giant shield and a Badass Mustache (actually the first reveal of upcoming champion Braum) who, after saving him, arranges his fur into a little mustache of his own.
Braum: Next time, you get my back, eh?
Braum himself is essentially a Crowning Character of Heartwarming in many ways. Not only is he a Spirited Competitor and ultimately friendly to every other Champion in the league, but this carries over into gameplay as well - his entire kit is dedicated to protecting his teammates and shielding them from enemy attacks. You will feel good playing this Champion or being supported by him. His W skill, titled "Stand Behind Me," is often accompanied by lines such as "Stand behind Braum!" or "And you thought you were in trouble." His whole personality can be summed up in one of his movement quotes:
Braum: "Sometimes icy heart just needs warm smile."
Compounding this is his backstory/lore. What was that, you thought he'd be a Stepford Smiler with a tragic backstory to make him look like a Sad Clown? Well, NOPE. Braum's lore is basically just yet another his folk tales about saving other people. He's always a positive Nice Guy from get-go and has always been as such from start to finish. There's no such thing as angst in Braum, he's genuinely friendly, cheery, supportive. Sometimes, in the world where 'edgy is cool' and True Art Is Angsty, it's always assuring that there are guys like Braum, like saying that you don't have to be dark and edgy to be cool, and being a Nice Guy isn't that boring, but awesome.
Azir's reincarnation story. Sivir has just been betrayed by Cassiopeia (who in turn, becomes cursed herself, and released Renekton and Xerath back upon the world) and left for dead. What's Azir's first thoughts upon returning from the dead due to Sivir's blood (having unknowingly been descended of his bloodline) and actions? He picks her up and takes her to a place with healing waters, and brings her back from the brink of death. This selfless act, causes him to receive the power of Ascension, and begin the revival of Shurima.
The reason Lee allowed his fellow monks to stop his self-immolation? His sister, who was living in Galrin (which was one of several Noxian-occupied provinces at the time), visited him after Ionia was liberated.
After a mutual hostility that lasted years of real time, the former partners Twisted Fate and Graves have resolved their differences. They're even officially listed as "Friends" on their respective champion bios. (Though you'd better believe they had to earn that reconciliation.)
Japan and PC Gaming aren't exactly the most compatible pair, as the latter is mostly having cult favorite status in the former (console and mobile gaming are bigger hits there). But then, Riot Games revealed on how they are planning up the Japanese server, and they're really serious on this, not only they bring forth several well-known Names to Know in Anime, these seiyuus (so far Sumire Uesaka (Jinx), Keiji Fujiwara (Master Yi), Aoi Yuki (Lulu) and Natsuki Hanae (Ziggs)) truly gave their all for this job (FujiKei even claimed to have traveled to a mountain to meditate, solely to prepare himself to the role of Yi) and are enjoying the work with Riot, Hanae has also recalled that he's actually an avid LOL player and did a lot of Ranked Games, attended local tournaments and has nothing but enjoyment recalling those memories (in spite of being Japanese, he'd have to content with the massive lags, and with the release of LOL Japan, he and the rest of Japanese players may get a better, less laggy environment). It might be small, but it's nice to see that even LOL, confined in a platform not that widespread in the Land of the Rising Sun, are well loved there beyond just fanarts.
The climax of Lucian's story in Shadow and Fortune. Throughout the story, Lucian has been waiting for his chance to get revenge on Thresh for murdering his wife Senna, although he's increasingly troubled by how he's starting to find it difficult to remember her face without looking at the locket he wears with her picture in it. When he confronts Thresh, the wraith is immune to his weapons and gloats that he tore their secrets from Senna's mind when he enslaved her soul, horrifying Lucian and driving him to a Heroic B.S.O.D.. When Thresh is about to finish him and claim his soul, Senna herself forces her way to the front of the crowd of hundreds of thousands of tormented souls trapped in the lantern and implores him to fight and live. Wrapping his locket's chain around Thresh's wrist and stabbing him through it with his silver awl, Lucian weakens Thresh's control over the lantern and Senna leads the souls in rebellion against the Warden, weakening his defences enough for Lucian to blast him with their twin relic weapons, forcing him to flee for his unlife. The Power of Love triumphs over the darkness and Lucian finds a new purpose in life beyond simple revenge- to finally free Senna from Thresh forever.
He caught the briefest glimpse of Senna’s face in the lantern and etched it on his heart.
Never again would her face grow dim in his memories.
[...] “Thank you, my love,” said Lucian. “My light.”
Reginald: Fear of Failure features Team Solomid's captain Andy "Reginald" Dinh and his tale of going from a troubled schoolkid to the leader of one of America's biggest teams. It's really inspiring and almost goes into Tear Jerker in a few parts.
"There's always gonna be that bad guy, and I don't mind being it."
Who says that even fandom can't make a heartwarming story, even if it's probably non-canon? Take a look at She Who Is Like A Sun To Me, which takes Pantheon's baker joke and Leona's protective instinct into a story of sweet friendship that may shed a lot more humanity on the war-worshipping Rakkor warrior, and launch the Pantheon/Leona ship even further. note The summary: Pantheon used to be a ostracized Rakkor kid because of his baking hobby, with everyone else bullying him for that, and only Leona staying as his friend, driving away the bullies and enjoying his cakes. Even as he became the paragon of Rakkor and their way of warrior, and Leona became a member of the Solari, Pantheon will always see her in high regard.
And if you look at the comments of the link... it looks like IronStylus loves this one.
Well speaking of Blitzcrank/Orianna, you may want to check out this short story Deus Ex Machina which involves some Tear Jerker, some Moment of Awesome, but most importantly, lots of feels for the two. Guest starring Viktor.