For reasons we can never know, fate brings friend to friend, then leaves the rest to human nature. The results are mixed. While a few special friendships last a lifetime, the vast majority prove easier to leave behind. Some take years to fade away; others end spectacularly. Research shows that the quickest way to end a friendship is betrayal; the second-quickest, a canoe trip.

In fact, we have to lose a few friends before we can appreciate their most important gift: the stories we share. In hearing these stories, you may begin to sense a deeper truth, that our friends and friendships are not as unique as we first believed. They’re more like summer movies: the dialogue changes (kind of) but the plots and characters keep recurring. Here’s a catalog of the archetypal friends that over the course of a life you’re likely to encounter again and again.

The Best Friend: The gold standard of friendships. A best friend listens but never judges, helps you out of a jam, tells it to you straight, and often forgives a debt. Best friends resemble invisible friends in that both are most common in childhood (and may not really exist).

The Old Friend: Ideally, a lifelong bond that stirs fond feelings and cherished memories—unless you’re a celebrity or out on parole. In reality, most old friendships are embedded in a complex economy of favors. President Bush rewrote the entire tax code for his old friends.

The Older Friend: Two varieties:
(1) Someone your senior who mentors you with wit and wisdom, as portrayed in the best-seller Tuesdays with Morrie. (2) The client of an escort service, as detailed in the cult classic Wednesdays with Brianna.

The New Friend: Generally speaking, a person who can do no wrong until you’ve had a few more outings together. New friends are more likely to enjoy your stories and show up on time. It’s also easier to be who you are with a new friend, as opposed to who you were—which is what you end up being most of the time with your old friends.

The Wild Friend: The friend whose bad behavior never ceases to entertainand may at times inspire you, for better or for worse. Though wild friends get a bad rap, they save as many lives as they ruin. Boring people—writers, for instance—desperately need wild friends.