Keep the new cat in a separate room at first
Give each cat its own food, water, litter box, bed, and toys
Let the cats get used to each other’s scent by swapping bedding or toys
Feed both cats on opposite sides of the closed door
Open the door briefly for short, supervised visual introductions
Use a baby gate or cracked door if needed
Watch for signs of stress or aggression
Keep early meetings short and calm
Reward calm behavior with treats or praise
Increase time together gradually
Do not force interaction
Separate the cats again if tension rises
Maintain separate resources until both cats are fully comfortable
Be patient and move at the slower cat’s pace