I am a relatively kind-looking, safe-looking, and reasonably sized young woman. For this reason, if there is an open seat next to me on a bus/train- people will sit there.
Girls will sit there because they see we have common ground, guys will sit there because I am a WOman, and old creepy guys will sit there because I am a WOman. (And the other kind are old women- they will sit there, too).
It doesn't seem fair to me that creepy or gross people get two seats to themselves, but I am always sat down next to, so I have developed a method for keeping people away:
1. Look super mean. I have learned I am quite good at this; just look pissed and angry. And bitchy: See this post, which is less of a helpful tutoral like this, and more of a sad revelry in my unkind ways.
1. a. Look BUSY and mean. Flip through papers frantically, look on your phone as if someone died, talk on the phone to an imaginary friend and flip out, go through your bag as if you just lost your wallet. Look mean while you do this. I have actually never purposefully done this, but I guarantee it will work. Scare people.
2. Sit on the aisle seat (preferably looking mean and frazzled) making it harder for them to slip into the seat. Then they have to ask you to move, and people are lazy and may avoid speaking, which is a score for Solitude.
3. Dirty the seat next to you. This one works very well. If you choose to sit by the window for any number of reasons (outlet/view/napping on the window, etc.) you will need to take action to make the aisle seat look undesirable.
One time I was sitting in the window, and the aisle seat next to me had all these train conductor clippings from when they punch the tickets with their spiffy, weird, hole-puncher. It looked messy and questionable and NOBODY SAT THERE, to my delight. This is when I began to cultivate my methods for keeping my solitude. Another time, I had been eating some oily italian meal, and had my wrinkled, oily napkin sitting on the seat next to me. NOBODY SAT THERE.
4. Bring a Smelly Meal. Whip out your tuna salad right when other people are entering looking for seats. Any way to gross someone out is a good way not to attract a bus-mate.
Some people hope to meet their soul mate on buses. I used to think that this would happen to me, but didn't want to be the one choosing my seat/soul/mate, so I would rush to a window seat first and wait for KISMET to occur.....
And- guess what! Only old ladies sat next to me and made my ride a joy by asking me a million questions during those rides.
So, I gave up on train love and started shunning people.
That's just the way it has to be.