Once an "only child," cat Jax was surprised with a new sibling in kitten Ava. After some initial skepticism, the pair developed an unexpected bond!

"Jax was an only child, spoiled like no other," the TikTok video's text explains. "Little did he know he was about to be a brother."

In the clip, Jax and the newly adopted Ava are then seen meeting for the first time. "Ava was brought home and was as loving as can be."

But Jax wasn't ready just yet, and he initially watched the "new girl" from a safe distance.

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"It took a bit of time, but they start to move close, and Ava was determined to give him a boop on the nose," the video reveals.

The initial teasing soon evolved into playtime, which eventually led to shared meals and cuddles.

"Doing things together started bringing them so much joy," the video said.

Jax began to take careful care of his animal little sister, especially when the kitten broke her leg in a fall off the sofa.

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Ultimately, Jax "learned to be the best big brother he could be."

In the video, the two kitties can be seen intertwined, sleeping together.

"To this day, all Ava wants to do is be beside Jax," the video, which has already garnered nearly 400,000 views, added.

The owners reveled in their dream come true, writing, "Who knew that adopting another cat would create a bond like no other."