Similarity is the most powerful predictor of friendship formation. This is not a controversial finding; it is one of the most replicated results in social psychology, consistent across cultures, age groups, and relationship types. People become friends with people who share their values, their communication style, their socioeconomic background, their education level, their sense of humor, and their worldview. Propinquity — physical proximity — and similarity work together to produce the social world most adults inhabit: a cluster of people who are, in most meaningful respects, variations on themselves.
This is efficient. It is also impoverishing.
The friend who is nothing like you — genuinely, substantially different in background, temperament, worldview, aesthetic sensibility, or values — offers something that no same-template friend can provide: access to a version of reality you are not constructing. Every person's perception of the world is shaped by their history, their cognitive style, their aesthetic training, their class position, their trauma, their luck. You see what your categories let you see. The friend who does not share your categories sees what yours filters out. You call it noise. To them, it is signal.
The catch is that this friendship is hard. Not impossible, but hard in specific ways that need naming. The first difficulty is finding a common language. Similarity-based friendships run on a shorthand that took years to build — shared references, shared assumptions, a vocabulary calibrated to the same frequency. With the unlike friend, there is no such shorthand. Every statement is a partial translation. Every laugh is a minor miracle — evidence that two radically different meaning-making systems have converged on the same absurdity. The absence of shorthand is not just inconvenient; it is diagnostic. It shows you exactly where your categories stop and theirs begin.
The second difficulty is tolerating being wrong in front of them. Your unlike friend will regularly reveal, not through argument but through example, that things you took for granted about how the world works are only true for a specific stratum of it. The revelation is not comfortable. Your default assumptions about how long things take, how much things cost, what counts as an appropriate amount of worry about money, what a normal childhood looks like, what authority figures are for, whether institutions can be trusted — all of this gets quietly dismantled in a friendship with someone whose formation was substantially different from yours. The dismantling is not an attack. It is evidence. Whether you receive it as such or defend against it determines whether the friendship deepens or stalls.
The third difficulty is asymmetric invisibility. If your unlike friend is from a more marginalized position — lower class, different race, differently abled, from a culture that has less institutional power in your shared context — then the costs of the friendship are likely distributed unevenly. They have to do more translation work, absorb more cluelessness, absorb more of the friction of being the different one in the pair. This asymmetry does not invalidate the friendship, but it must be acknowledged and not left entirely for one party to manage. The unlike friend who carries all the translation burden and none of the benefit of being genuinely known is not in a friendship. They are in a performance of one.
What you get, when the friendship works, is a persistent check on your own parochialism. Not a lecture — the friend who is nothing like you is not there to educate you. But the sustained fact of their presence, the way they handle situations you would handle differently, the things they notice that you walk past, the things they do not notice that you cannot stop seeing — all of this works on you over time, slowly, in the way that long exposure to a different climate changes your physiology. You become less certain that your way of navigating the world is the only way. That is not a loss. That is one of the few forms of actual growth available to an adult.