What to Expect:
When you bring your kitten home, you can keep your kitten in a room within a few strides reach of you while your other pets are nearby. Usually the first stage of meeting starts with curiosity and then distrust. So a cat may come up to investigate the kitten and then quickly hiss and retreat. This will probably happen a few times. They may stay at a distance while cautiously observing the kitten and quietly growling to show their mistrust. Hissing and growling are all acceptable behaviors but you should react if physical aggression, such as attacking or swatting while hissing/growling, occurs. Cats can wrestle and tussle but they shouldn't be doing so while hissing/growling. The next stage is quiet acceptance. At this point, the other pet will tolerate your kitten and won't react much. The last stage, while it may never happen, is affectionate bonding where co-sleeping and social grooming or playing together can all occur. How long each phase takes and if the last phase even happens depends on several factors.
What Factors Are Involved?
The temperament of your pet has the most impact on whether they become friends. Easily accepting change and being very sociable to people or other animals are all good signs. The age difference can also impact the type of relationship formed. A closer age gap could cause a brother/sister sibling type of relationship whiles a greater age gap could change it to more of a parent/child. Space can also have an impact. Animals tend to require a certain degree of space for themselves and where their space overlaps with another animals can give tension. The more space afforded, the less stressful the situation is. Gender is another consideration. Neutered males have no social role and therefor are more laid back, less territorial, and generally like everyone with no preferences. Females, spayed or not, always have a maternal drive and this drive can get stronger with age. This tends to make females more protective and therefor choose particular people to protect and a territory in which to protect. While 2 females aren't doomed to dislike each other, more often than not, when someone asks a feline behaviorist for help in cat disputes it's 2 females involved. Therefor, opposite sexes or 2 males have more success. Breed can change the dynamic as well. While most breeds are known for certain behavioral characteristics that can impact interaction, most cats and dogs become more sedentary as they age. Bengals, however, are a breed that are known for retaining their kitten-like energy and curiosity throughout their entire lifespan. Bengals can easily overtire and pester other animals into playing with them and become easily bored. This is one really good reason why another Bengal is the best lifelong playmate for a Bengal.
What can I do to help my pet accept my new kitten?
During the day while you are around you can keep your kitten close by while observing the interactions. As long as there is only hissing and growling then you can continue to let your pet investigate and accept your kitten on their terms. When you are not around and at night, the kitten will need to be isolated from your pet until you feel confident the kitten will be safe. The kitten's natural playful side should help to bring out your pet's curiosity and playfulness. If your kitten and pet are playing together, make sure the kitten is not getting hurt and not acting scared. If the kitten is running back for more, instigating play, and acting normal than a little rough-housing is nothing to be alarmed about.
At any point, if there is physically aggressive behavior you will need to use a much slower approach that involves keeping your kitten completely isolated. Take blankets that the kitten has slept with and use them to introduce the pet to the kitten's scent. You can bring the kitten out for short periods of time for supervised play around your pets and slowly increase the time. If aggressive behavior is still witnessed, the time your kitten is around needs to decrease or stay the same and not increased until your pet shows improvement in accepting your kitten.
In either approach, you can help quicken the pet introduction phases by using positive reinforcement. You should find a tasty treat your pet enjoys and give that whenever your pet comes to investigate your kitten as a reward for being around the kitten. For dogs or cats, I find that cooked or uncooked hotdog pieces work very well as they are easy to chew and have a strong smell and taste. I would say to reward frequently, say every 5 minutes, while your pet interacts positively or hangs around the kitten. As time goes on, you can reward less and less frequently. You want to create a positive association with your kitten. You can alternatively or in conjunction use praise and give a lot more attention as a positive reinforcement as well. You may also try to use the playful nature of kitten and pet to bring out positive interactions by using a feathered wand or other play tool.
Lastly, a great product on the market that should help cat introductions is Comfort Zone. The name says it all as it is a pheromone based system that helps to create a calming environment for cats. The diffuser has refils that need to be replaced every month and should be set up at least 2 weeks prior to the arrival of your kitten to have an immediate impact.