The Melancholic temperament has three combinations: Melancholic-Choleric, Melancholic-Sanguine, and Melancholic-Phlegmatic.
The traits of the primary temperament, Melancholic, may be altered or modified in some significant way due to the influence of the secondary temperament. Remember, there are at least three levels of intensity of a temperament: classic, moderate, and mild. Some Melancholies will be very strong, others somewhat strong, and still others more mild.
Melancholic is traditionally understood as being fundamentally unstable (defined as "strong emotions") and introverted (defined as "long-lasting emotions").