Temperament

Siamese are affectionate and intelligent cats, renowned for their social nature. They enjoy being with people and are sometimes described as "extroverts". They are extremely vocal, with a loud, low-pitched voice – known as "Meezer", from which they get one of their nicknames[2] – that has been compared to the cries of a human baby, and persistent in demanding attention. They also have a great need for human companionship. Often they bond strongly to a single person. These cats are typically active and playful, even as adults.[3][4]

The social orientation of Siamese cats may be related to their lessened ability to live independently of humans. Siamese coat colouration is appealing to humans, but is ineffective for camouflage purposes. They are less active at night than most cats, possibly because their blue eyes lack a tapetum lucidum, a structure which amplifies dim light in the eyes of other cats. Like blue-eyed white cats, they may also have reduced hearing ability. Therefore, being dependent on humans may have been a survival trait for ancestors of the Siamese.

Source : http://en.wikipedia.org/wiki/Siamese_(cat)