It is a fate you wouldn't wish upon your enemies. It's a form of cruel and unusual punishment. It's a curse that can plague a third of passengers on any given flight.

It's the middle seat, and, technically speaking, it's the worst.

Aside from parents and people flying in groups, few fliers choose to sit here. After you book your ticket and it's time to reserve your seat assignment, you'll find a glut of middle seats lingering before the plane fills up. On Southwest, whose policy makes passengers pick seats after they board, people boarding late are relegated to being sandwiched.

Airplane seats are already too small to be comfortable, so why would you want one wedged between two strangers? Not only are your legs crammed into the back of the seat in front, but you also typically have body parts of the passengers on either side ramming into you repeatedly.

If you get lucky with good neighbors, there are still the inherent issues of the seat's placement. You're trapped by the aisle-seat passenger, unintentionally restricting your access to the lavatory and overhead compartments. You're in an awkward spot if you want to look out the window. You may know you're taking in the horizon, but to the window-seat passenger, it feels like you're staring right at their head.

There are many cons and few, if any, pros. Here are the rules of the middle seat for those who are stuck there.

Rule 1: The middle seat owns both armrests

This rule is so important that it should be engraved onto the doorway of the plane or included in the safety video that plays before takeoff that people are definitely watching. Passengers in the surrounding seats must be made aware.

The mandate is this: The middle-seat passenger gets both armrests, period. Do they have to use them? No. But should they be made available to that cursed soul trapped in airplane purgatory? Yes. It's not a conversation. It's not an argument. It's a given. Offering up both of those tiny little ledges that provide minimal relief is the least that can be done.

Rule 2: The middle seat must not exploit its position by annexing more leg space

Yes, you are jam-packed into your row like a middle pea in the world's least comfortable pod, but that does not mean you can let your legs flail open, into the limited personal space of neighbors. Leg space is sacred. Respect the invisible boundaries that extend from the armrests down to the plane's soiled carpet. Note that knocking knees with strangers is also not OK, either. Although your arms and shoulders are likely to touch your neighbors', wrangle your legs together. Keep them to yourself.

Rule 3: The middle seat must not sleep on anyone's shoulder

Waking up to find yourself snoozing on your seatmate might have been cute when you were a kid, but it's not a good look as an adult. Be mindful of teetering over too far and ending up on a neighbor's shoulder. Using a stranger as a pillow without their permission sends a weird message. Save yourself the embarrassment of waking up mid-drool by focusing on sleeping upright. A travel neck pillow that straps to your headrest might help drifters.

Rule 4: The middle seat must be taken if traveling in a couple

The middle is the worst. We've established that. But if you're traveling as a couple, one of you must claim it. Cursed are the couples who opt to book the aisle and window seat to avoid the center, leaving a stranger to endure two lovebirds talking and passing things across the row.

For the love of all that is holy, don't split up. Someone be an adult and sit in the middle.

Rule 5: The middle seat should at least attempt to time lavatory visits with the aisle seat

This rule pertains to the passenger seated next to the window, as well. While the other rules on this list are more stringent and should be treated as law, this one is less a necessity and more of a recommendation for being a good neighbor. If your body allows it, wait until the other passengers in your row get up, for whatever reason, to make your trip to the lavatory. It's not the end of the world if you have to ask them to get up just for you, but it's nice to be considerate of timing, particularly if they're sleeping.

This courtesy extends beyond bathroom use. Be mindful when you board to store what you need below the seat in front of you, so you don't have to get up throughout the flight to access the overhead bin to rifle through your carry-on.