During Fat Bear Week, when brown bears bulk up for winter, an unlikely friendship has arisen.

A brown bear and her offspring don't spend much time with other bears. Two mothers with a single baby formed a ursine quartet that has been fishing and playing together.

During Fat Bear Week, fans can vote for their favorite fat bear in a tournament. Explore.org is a website that hosts various animal-centered livestreams.

The bears known to humans as bears 912 and 912 are actually sisters, though this doesn't make their current close relationship less noteworthy.

Mike Fitz, Explore.org's resident naturalist, said he had never seen families associate with each other like these.

Two brown bears (not 909 and 910) fishing for salmon at Katmai National Park. (Photo: Gilles MARTIN/Gamma-Rapho via Getty Images))
Two brown bears (not 909 and 910) fishing for salmon at Katmai National Park. (Photo: Gilles MARTIN/Gamma-Rapho via Getty Images))

There are two brown bears fishing for salmon at the park. The photo was taken by Gamma-Rapho.

Naomi Boak said that the friendship was the "story of the year" for her.

The beginnings of Fat Bear Week can be dated back to 2004. Fitz posted pictures of the bears on the park's Facebook page and encouraged viewers to vote for their favorite.

Fitz said that the one-day event, Fat Bear Tuesday, had a high level of engagement.

Fat Bear Week was born after the park staff decided to make the voting week long. The annual bear-to-bear contest has grown in popularity, and the winning bears get a lot of attention.

Charles Annenberg Weingarten, the founder of Explore.org, said that fans return to the area every year, and it fills them with joy.

Otis, a 25-year-old bear who had experienced some health issues earlier in the year, was voted the favorite bear last year.

Otis, the reigning champ of Fat Bear Week. (Photo: Lian Law/U.S. National Park Service/Handout via REUTERS)

The reigning champ is Otis. National Park Service/ Handout

As of Saturday afternoon Otis was still in the running for the title.

The winner may be the best bear.

The article was first published on HuffPost.

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