A kitten's transformation, from hostile to friendly, after being adopted by a loving family has tugged at the heartstrings of viewers online.

The kitten, who had once been described as "aggressive," was shown to gradually grow in confidence and ease in an Instagram post by @oreo.and.newt from June 21. The black and white kitten, named Oreo, had been taken in by a family with an existing pet—another cat, named Newt. To their owner's delight, the pair eventually began showing affection towards each other with Oreo coming out of her shell, something that was captured in the post that has been viewed more than 1.7 million times.

Viewers initially saw Oreo staring cautiously at her new surroundings, hissing at her owner and fleeing under beds and couches any time they attempted to approach her. In contrast, by the end of the clip, the kitten was shown sitting comfortably beside her older sibling and offering both warmth and affection to her adopters.

The video closed with a shot of Oreo moving towards her owner to be stroked and given attention.

"Omg! This was such an awesome moment! We knew she could do it! All the patience, hope, and loves we gave her, so worth it! Thanks to Newt who helped her feel safe around her new human family," the cats' owner said.

The pets' story proves that introducing a new kitten to an existing cat can be a delicate process, requiring patience and careful planning to ensure a harmonious household.

The Royal Society for the Prevention of Cruelty to Animals (RSPCA) advises owners keen to introduce existing cats to new kittens to start by keeping the incoming kitten in a separate room, allowing the resident cat to get accustomed to the newcomer's scent.

The charity adds that owners should eventually introduce them through calm and supervised interactions, providing plenty of positive reinforcement, treats, and affection to both.

Over time, and with consistent gentle introductions, most cats can adapt to a new companion, fostering a peaceful and friendly environment.

More than 171,000 viewers have liked the video, while others have shared their thoughts on Oreo's development in the comments section.

One user, @tinsleydena, said: "Why do they label them like that, she is just a little spicy."

Another, @flowersandsuch121, added: "She wasn't aggressive, she was frightened."

"You did it! I'm so happy! The gasp I let out when she came over for pets," a third user, @shortstoriesaboutlife, added.

Newsweek reached out @oreo.and.newt for more information via Instagram.

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