Introducing a new cat requires a gradual, step-by-step process, centered around managing territorial instincts and building a sense of security. Typically, an adjustment period of 1–3 months is needed.

Initial Isolation (1–2 Weeks)
Prepare a separate room for the new cat, equipped with all the essentials (litter box, hiding spots, food, and water). Use pheromone diffusers in advance. During this phase, avoid direct contact and only allow scent exchange under the door.

Scent Integration (2–3 Weeks)
Systematically exchange scented items between the cats: start with socks rubbed on their cheeks, then move on to blankets and toys. You can also implement "space rotation"—letting each cat explore the other’s area at different times, while engaging in positive activities like eating or playing in that space.

Visual Contact (Starting Week 4)
Use a safety gate or barrier to allow the cats to see each other. Begin with short sessions of 2–3 minutes, paired with high-value treats. Watch their body language: slow blinking or looking away are positive signs; stiff staring, raised fur, or growling mean they should be separated immediately.

Long-Term Coexistence Management
• Follow the "N+1" rule for resources (one more litter box than the number of cats)
• Place food and water bowls separately to avoid competition
• Develop vertical space (cat trees, window perches)
• Ensure each cat has daily alone time

Signs Requiring Intervention
Seek advice from a cat behavior specialist if you observe ongoing aggression, excessive hiding (more than 2 weeks), refusal to eat, or overgrooming to the point of hair loss.

Success is measured by the cats being able to coexist calmly in the same space while maintaining a respectful distance. Patient observation and gradual guidance are more important than forcing interaction.