When you’re a kid, or in high school or college, you usually don’t have to work too hard on your friendships. Friends just kind of happen.

For a bunch of years, you’re in a certain life your parents chose for you, and so are other people, and none of you have that much on your plates, so friendships inevitably form. Then in college, you’re in the perfect friend-making environment, one that hits all three ingredients sociologists consider necessary for close friendships to develop: “proximity; repeated, unplanned interactions; and a setting that encourages people to let their guard down and confide in each other.” More friendships happen.

Maybe they’re the right friends, maybe they’re not really. But you don’t put that much thought into any of it. You’re still more of a passive observer.

But once student life ends, the people in your life start to shake themselves into more distinct tiers.

It looks something like this mountain:

At the top of your life mountain, in the green zone, you have your Tier 1 friends: the people who feel like brothers and sisters.

These are the people closest to you, the ones you call first when something important happens, the ones you love even when they suck, who make speeches at your wedding, whose best and worst sides you know through and through, and whose relationship with you is eternal; even if you go months or years without hanging out, nothing has changed when you find yourself together again.

Unfortunately, depending on how things went down in your youth, Tier 1 can also contain your worst enemies, the people who can ruin your day with one subtle jab that only they could word so brilliantly hurtfully, the people you feel a burning resentment for, or jealousy of, or competition with. Tier 1 is high stakes.

Below, in the yellow zone, are your Tier 2 friends: your Pretty Good friends.

Pretty Good friends are a much calmer situation than your brothers and sisters on Tier 1. You might be invited to their wedding, but you won’t have any responsibilities once you’re there. If you live in the same city, you might see them every month or two for dinner and have a great time when you do, but if one of you moves, you might not speak for the next year or two. And if something huge happens in their life, there’s a good chance you’ll hear it first from someone else.

Toward the bottom of the mountain in the orange zone, you have your Tier 3 friends: your Not Really friends.

You might grab a one-on-one drink with one of them when you move to their city, but then it surprises neither of you when five years pass and drink #2 is still yet to happen. Your relationship tends to exist mostly as part of a bigger group or through the occasional Facebook Like, and it doesn’t even really stress you out when you hear that one of them made $5 million last year. You may also try to sleep with one of these people at any given time.

The lowest part of Tier 3 begins to blend indistinguishably into your large group of acquaintances (the pink zone): those people you’d stop and talk to if you saw them on the street or would maybe email for professional purposes but whom you’d never hang out with one-on-one. When you hear that something bad happens to one of these people, you might be sad but not too affected.

Finally, acquaintances gradually blend into the endless world of strangers.

And depending on who you are and how things shook out in those first 25 years, the way your particular mountain looks will vary.

For example, there’s Walled-Off Wally:

And Phony Phoebe, who tries to be everyone’s best friend and ends up with a lot of people mad at her:

Even Unabomber Ulysses has a mountain:

Whatever your particular mountain looks like, eventually the blur of your youth is behind you, the dust has settled, and there you are living your life.

Then one day, usually around your mid or late 20s, it hits you: It’s not that easy to make friends anymore.

Sure, you’ll make new friends in the future, at work, through your spouse, through your kids. But you won’t get to that Tier 1 “brothers” level with very many of them, or even to Tier 2. That’s because people who meet as adults don’t tend to get through the 100-plus long, lazy hangouts needed to reach a bond of that strength.

As time goes on, you start to realize something. The 20-year frenzy of haphazard, not-especially-thought-through friend-making you just did wasn’t random. It was the critical process of making most of your lifelong friends.

And since you matched up with most of them A) by circumstance, and B) before you really knew yourself yet, the result is that your Tier 1 and Tier 2 friends—those closest to you—fall in a very scattered way on what I’ll call the Does This Friendship Make Sense? Graph:

So, who are all those close friends in the three non-ideal quadrants?

As time goes on, most of us tend to have fewer friends in Quadrants 2 through 4 because A) people mature, and B) people have more self-respect and higher standards for what they’ll deal with as they get older. But the fact is, friendships made in the formative years often stick, whether they’re ideal or not, leaving most of us with a portion of our Tier 1 and Tier 2 friendships that just don’t make that much sense. We’ll get to the great, Quadrant 1 friendships later in the post, but in order to treat those relationships properly, we need to take a thorough look at the odd ones first.

Here are 10 common ones:

1. The non-question-asking friend

You’ll be having a good day. You’ll be having a bad day. You’ll be happy at work. You’ll quit your job. You’ll fall in love. You’ll catch your new love cheating on you and murder them both in an act of incredible passion. And it doesn’t matter, because none of it........

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