This introduction succeeds by protecting what your resident cat already trusts: his territory, his timetable, and his freedom to ignore the newcomer for a while. The kitten, meanwhile, needs one secure base room rather than the whole house. Set that room up before she arrives, with a litter tray away from her food and water, a hiding box, bedding, and something to scratch. Your adult cat should lose nothing on arrival day: no moved bowls, no borrowed bed, no closed-off favourite window. Cats negotiate through scent and routine far more than through a dramatic first hello.
Scent Work Before Sight
For the first several days, the cats know each other only by smell. Stroke a soft cloth along the kitten's cheek and leave it near, not on, the resident cat's resting place, and do the reverse with a cloth carrying his scent in her room. Swap bedding once both animals have slept on it. Watch the reactions closely: sniffing and then carrying on is excellent, rubbing against the cloth is better still, while hissing at the scent means the pace is already fast enough and should not increase yet. Feed meals progressively nearer the closed door on both sides, so each cat pairs the other's smell with dinner rather than with an ambush. Keep the resident's play sessions and lap time exactly where they were.
Seeing Each Other Without Touch
Once both cats eat calmly near the door and investigate swapped bedding without agitation, add vision through a secure gate, a mesh door, or a door opened a crack and wedged safely. Let them look, eat, and play in parallel, with a person on the kitten's side and escape routes behind both cats. A hiss or a short stare is communication, not failure. What should pause progress is fixed staring with a lowered, tense body, stalking that repeats, growling that does not settle, or either cat refusing food near the barrier. Drop back to scent only for a day or two, then try again. Short daily repetitions at this barrier stage do most of the real work of the introduction.
First Time in the Same Room
Choose the resident cat's less precious territory, not his core sleeping area, and keep the session to a few minutes. Scatter treats, offer two separate wand toys, and let the adult approach or leave exactly as he wishes while the kitten is gently prevented from rushing him, cornering him, or bouncing onto him. End while things are still mildly interesting rather than exciting. Increase shared time gradually, add supervised meals at a generous distance, and only allow unsupervised access once they can eat, pass, and rest in shared space without guarding doors, trays, or people. Resources should be duplicated during this period: separate feeding stations, water in more than one place, and at least one tray per cat plus a spare, placed apart so neither cat controls the only route.
Setbacks and the Longer View
Expect the resident cat to set terms for weeks. Some adults play with a kitten within days; others tolerate her at a distance for a month before sharing a sofa, and that slower outcome is still a success. Restart from the last calm stage after any real fight, and speak to your vet if either cat stops eating, hides persistently, or starts toileting outside trays, because behaviour changes around a new arrival deserve a health check as well as a training answer. Keep a brief daily note of door feeding, barrier reactions, and shared minutes so everyone in the home judges progress from evidence rather than one dramatic moment. Families sharing those duties can record each stage inside the Care Teams area that KinsLe provides for each cat's care.