London, UK - When Runi the dog kept licking his foster sister Anka's face relentlessly, his owner had no idea why. When she found out the real reason, she was touched.

The clip, which was shared on TikTok, shows a touching scene.

In a loving moment, Runi leans over to Anka, who is lying on a bed, and begins to lick her face tenderly.

Dog mom Yaprak, who cares for stray animals, initially thought it was a harmless quirk: "Runi likes to lick everything," she told Newsweek.

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But as the habit became more frequent, she began researching and discovered a startling truth.

Through licking behavior, dogs express affection, protection, trust, and deep connection. An adult dog licks another dog's face to say, "I'm protecting you."

Anka was rescued from Serbia and placed with the charity Balkan Underdogs. When Yaprak took her in, she was scared, withdrawn, and traumatized. But then Runi came along.

"It was like having a big brother always looking after you, which Anka certainly needed," said Yaprak. "I knew he was her guardian angel and I did get emotional."

The cute clip went viral on TikTok within a short time and moved many viewers.

"Anka was returned because she had a bad experience with their dog and our dog is reactive, so it could've been a recipe for disaster," Yaprak explained. "But Runi has been very patient and has not once growled at Anka, it was like a miracle."

The characters of the two dogs are quite opposite!

"Runi is very hyper, and all he wants to do is play," the woman said. "Anka is happy to chill on the bed all day doing absolutely nothing. She doesn't care if she goes on a walk or not."

Anka has since moved on to her new home, but she will never be forgotten by her foster family.