The term "sympathy" originally comes from Latin. It describes a spontaneous affection towards a person on an emotional level. A reflexive aversion is also possible, referred to as "antipathy." Sympathy describes the ability of a person to sympathize with both the joy and the suffering of his counterpart and to create the feeling of an inner kinship with this person. The sympathy usually arises automatically and apparently for no reason. Therefore, it can be difficult for the person concerned to justify why one person seems sympathetic to him fully and the other does not.
So sympathy is closely related to empathy. The more we empathize with the other person's feelings, thoughts, and actions, and the more we can empathize with them, the more sympathetic they are to us. Antipathy could therefore be based on a certain foreignness of the person, in the sense of the lack of comprehensibility of their words or actions from our subjective point of view.
Simply, sympathy works as follows: We are sympathetic to ourselves, and accordingly, people are more sympathetic to us the more they resemble us. Moreover, these people seem more predictable because we infer those of our counterparts from our thoughts, values, and actions, which quickly creates a high level of trust. So sympathy is also closely related to trust.
Usually, we speak of sympathy or antipathy very quickly. Either we want to get to know someone better, or we don't. This first impression is not realistic but a distorted picture of the person. We may find the new work colleague likable because she reminds us of our sister, or we find the new boss unsympathetic because he resembles a horror teacher from school. Therefore, it is good and vital that you learn to be aware of your feelings of sympathy or antipathy - but first of all, distrust them.
Because sympathy is never final, the tide can turn quickly as we find someone sympathetic. Perhaps you will expose him using a lie; over time, behaviors will emerge which are unacceptable to you, or he will make jokes at your expense that you do not find funny at all. And immediately, you see the once likable person repulsive. Such an error is often found in people with narcissistic or psychopathic traits. Such personality disorders are initially expressed through a high degree of charisma and sympathy. In the long run, however, you gradually expose the lies, manipulation, and emotional coldness that lie behind the facade. It is not uncommon for you to ask yourself afterward in disbelief how you could be so mistaken about the person.
Fortunately, the mechanism also works the other way round. It may be more difficult and tedious to convert an antipathy into sympathy than the other way around, but it is always possible. Sometimes you first have to know someone better to discover and appreciate their true qualities. Perhaps your colleague's laughter is too intrusive and loud for you initially, but you notice the funny and good-natured person behind it over time. Or the boss seems too dominant to you at first glance but suddenly appears very understanding, empathic, and human in a crisis - and your once negative image begins to change.