Hi Megan
Thank you for reaching out for professional advice. Cats can sometimes ‘figure it out’, but relying on this approach can often lead to long-term conflicts and chronic stress.
A slow, structured introduction process is essential to start on a positive note and prevent territorial fears and ongoing disputes.
First thing, plug in a Feliway Friends/MultiCat. This is useful if any conflict arises between the cats during introductions or if their relationship breaks down later. The diffuser should be plugged into the areas of the home where the cats spend most of their time or where conflict or tension occurs most often. Spraying Feliway on prominent resources can also aid with the introduction phase.
Second thing, restart the introduction process. Please don’t rush or skip any of the steps, and watch for negative behaviors. Generally, whenever there’s conflict or cats display negative behavior(s), revert to the previous step in which both cats were calm in each other’s presence. Moreover, don’t feed the cats their regular meals at either end of the barrier. This is a common mistake that I see proposed online. Cats are solitary hunters and feeders; they prefer to eat alone.
Both cats should always be able to avoid and escape each other, especially if one kitten is likely to direct unwanted play behavior towards another kitten with a different temperament.
Another tip: If both cats enjoy brushing, use a slicker–type brush to mingle their scents by letting your resident cat sniff the brush. If they aren’t hissing or showing negative behaviors, brush them gently for a few minutes daily; do the same for the new cat.
I hope that helps.
Melina