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!"
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.
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."
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.
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.