The cats, Gin and Tonic, live together with their owner and have received attention worldwide since a video of their bond was posted on the TikTok account happyvanja.

With the caption: “This is soooooo damn cute,” the video shows older cat Tonic and sister Gin walking together through the house, with Gin never more than a few steps away from her idol.

The text overlay read: “When your sister is your hero,” and the 19-second clip follows Gin as she sticks close by to her companion.

Cats, like humans, have a range of different personalities. While some love the company of other animals, others prefer to be left to their own devices. Experts advise that it is important to think very carefully before introducing another cat to your household.

While cats will often be friendly with other cats they grew up with, they may not accept a new friend.

Author and Cat Behavior Associates expert Pam Johnson-Bennett told Newsweek: “Introducing a kitten to an adult cat requires making sure the cat doesn’t get overwhelmed by the energetic little newcomer.

“Kittens don’t have a strong sense of territory yet and they certainly have an endless supply of playful energy. That playfulness can be too in-your-face when it comes to an adult cat.”

Introducing cats and kittens takes time, and it is important to take small steps and avoid the big mistakes when introducing new friends to prevent an adult cat’s sense of territorial protection from taking over.

When done correctly though, cats can quickly become the best of friends—just like Gin and Tonic.

In over 1,100 comments, viewers of the now-viral video rushed to share their reactions to the adorable footage.

One reply said: “The kitten’s version of personal space reminds me of my kids, so cute,” while another TikTok user wrote: “This is beyond adorable.”

“They are both so gorgeous,” wrote another viewer. “Omg this is just cuteness overload,” gushed one reply.

Far from the only cats to melt hearts online with their close relationship, last year two identical cats cuddled up, which prompted pet owners around the world to share pictures of their pets spending time together.

Earlier this year, cat owners were left in stitches after seeing a relatable video that highlighted sibling rivalry between two cats that people said was “so true.”

Newsweek has reached out to happyvanja for comment.