Frozen Abominable Guardians (also known as A Wintery Family, Frost Family or The Frosts) is a EU (Extended Universe) within the Big Four Fandom. This Alternate Universe suggests that Jack and Elsa adopt the young yeti Everest from DreamWorks' animated film Abominable in a world where Elsa and Jack end up together. Because it is not canon, ideas for this AU are shown through fanfiction, fanart, and other fan-made works. This AU is considered to be an extension of the Jelsa pairing, Frozen Abominable and even to AUs like Seasons Guardians AU.
About the EU
This universe was created after two DeviantART users, Serpanade-Toons and Shinigamilover2 came up with the idea of Jack and Elsa finding Everest, decided to adopt the young yeti and care for him like he is their child. Fans saw this and began to support the idea that is part of Serpanade-Toons' Multiverse/Serpyverse that she shares with her friends on DeviantART, and it supporting both Mericcup and Jelsa sometimes allows it to be merged with the Big Four fandom from time to time, similar to how the Just-Ice League crossover fandom sometimes merges with the Secret of the Incredible Frozen Guardians EU.
The setting usually takes place after the events of Frozen II. All three of them have magical powers and have connections to winter, Elsa and Jack being an winter and ice spirits and Everest being a yeti from Mount Everest. Everest has white fur, like Jack Frost's winter spirit hair color. Jack knows the yetis who work for North, as well as him getting along with Toothiana's tooth fairies and Jack being the Guardian of Fun allows him to get along with children. Just as Elsa is shown to be as she make children smile with her powers, and Everest as had a lot of fun with Yi and her friends on their journey. Because many fans like to believe that Elsa became an immortal like Jack after she becomes the fifth spirit of Ice, and she has formed close bonds with the Enchanted Forest's four elemental spirits. This theory has allowed the setting of the EU to also be placed in the 21st century era, like both Rise of the Guardians and Abominable are. Some of the fanart sometimes has the three with an OC of Jack and Elsa's child, who Everest becomes a brother to.