Melancholic

In a nutshell...

Melancholic people are emotionally sensitive, perfectionistic introverts.

Perfectionistic

The defining feature of a melancholic attitude is perfectionism. They are idealists who wish for things to be a certain way, and they get distressed when they are not.

They hold themselves and others to unrealistically high standards, and get distressed when these standards are not met.
This leads to them being self-deprecating - because they do not meet their own standards - and critical of others - because those others do not meet their standards.

Their generally dour demeanour comes from their inner struggle between an imperfect world and a desire for perfection.

Many melancholics wish to learn and to understand, to know the details of every little thing, because to be ignorant is to stray from perfection. They are not content to just accept things the way that they are.
They are inquisitive and ask specific questions in order to come to a clearer understanding.

This leads many of them to be overanalytical, neurotic worriers.

They are very stubborn, because they try very hard to stick to their own carefully considered views and standards of perfection, and are not easily shifted from this path. They do not go with the flow.

They are tenacious and cannot let things go, because 'good enough' is not good enough. They strive for perfection.

They are very pessimistic, and assume the worst due to these unrealistic standards.

They think and plan before they act; they are not the types who will resort to rash, impulsive behaviour, and will panic if they are unable to plan in advance.

It's easier for them to reject and hate things than it is for them to love and embrace them. Their interests and tastes are picked carefully, and they give a lot of attention to each one, and hold them close to their hearts, rather than having many fleeting interests that change quickly and often.

They complain a lot, in a 'whinging' kind of way rather than a 'put down' or 'demanding' kind of way.

They tend to argue, because they cannot simply let things be if they seem wrong. They argue using reason, evidence, logic, and explanations, delivered analytically or with pleading. They only argue to set wrongs right, rather than to assert dominance. The argument is about the issue, not about them.

They respond poorly to compliments, often 'rebutting' them by saying that they're not so great after all.
"Wow, that's a really nice painting you just made!"
"I don't know, the eyes are probably too big..." (rather than "Thanks!")

They will blame themselves for mistakes, because they are acutely aware of their own imperfection.

They tend to prefer things to be tidy, organised in some way or another. This doesn't necessarily mean 'neat' as such; often they have very idiosyncratic organisation methods.

They are idealists, who imagine perfect fantasies and feel upset when things don't live up to these fantasies.

They prefer to tackle the heart of the matter, which can lead to them avoiding 'beating around the bush'.

Introverted

Melancholics are the most introverted of the temperaments in that they crave time alone, and are most at ease in their own company.

They can enjoy spending time with others, but this drains their energy, and they need alone time in order to recharge.

Much of their introversion comes from their perfectionism. They are picky about the sorts of people that they associate with; people who meet their standards and share their outlook. People that don't will make them uncomfortable; they do not wish to talk to 'anyone and everyone'.
Their self-deprecation also makes them think that they might not be very interesting anyway, that they aren't really worth spending time with, even if they know in the depths of their minds that they are very interesting indeed.

Once they have someone to talk to in a quiet and relaxed environment, they can talk a lot and will enjoy sharing thoughts and ideas.

They are very wary of making friends. Unlike sanguines, it can take them a very long time for them to consider someone they're familiar with a 'friend', but once they've reached this point, they will likely stick with that person loyally.

They prefer having a few close friends to many acquaintances.

They can be seen as selfish, because they prefer to be alone with their thoughts, to have their own things, rather than sharing time or possessions socially with others.
They are usually very possessive about the things that they own and are reluctant to let others borrow or use them, because they treat their own things well, care about everything deeply, and will worry that others will not look after them with the same level of care.

They could be described as 'intense', rather than 'easy-going'.

Sensitive

Melancholics are very emotional. They are moved deeply by beauty, and by distress. They are very easily hurt, because of their perfectionistic tendencies.
Often their moods are like delicate glass sculptures; built up slowly, deliberately, and carefully, but easily broken, and hard to repair once shattered.

They respond to things that they dislike with misery and with tears rather than with rage.

They are very slow to 'snap', but will hold onto emotions for a very long time. They hold grudges, because people who have failed to meet their standards, who have hurt them, will not just suddenly meet those standards without changing drastically.

They can become very 'moody', and they can be difficult to interact with because they are so easily hurt.

They are not aggressive, and wish to flee from things that cause them distress.

If they want to get back at another person, they are more likely to make them feel guilty than to insult them bluntly.

They are 'thin-skinned'.

Role

In our distant ancestors, the melancholic members of a pack may have been the analysts, the information gatherers. They scouted for potential danger, or for food, and reported back to the pack leader. The more accurate their findings were, the better; this led to a trend towards perfectionism, as the 'analysts' closer to perfection survived better than those that made sloppy mistakes.

In current society, they often tend towards analytical roles such as scientists, analysts, programmers, logicians, and so on. In fantasy settings, they may be wizards or sages.