Not everyone likes them. Sometimes you cannot stand them. It's a luck of the draw really. I got pretty lucky. My roommate and I are incredibly different, but we mesh really well. She's clean and I'm messy, but I keep my mess out of her space and she ignores that a small swamp (one which she and my friends affectionately refer to as "Little Florida") is growing out from underneath my bed.
I like food, and I'm willing to try anything once, but she's a food inventor. She eats the craziest things and I try them so that I can honestly say it's gross. I love video games and she really doesn't get them at all, but she's willing to listen to me talk about them, for a while at least.
The important thing here is that we started our roommate relationship before our friendship. We respect one another's space and privacy and accept each other's neuroses (ok, mostly my neuroses, but whatever) as part of the other person. We built a place that both of us feel safe in and like to come home to after classes.
Now that all of that mush is out of the way, we mostly are awesome roommates because of the AMAZING stuff we do together. At the beginning of the year we bought a painting in a thrift store and carried it (together) miles (I'll say about four and she'll correct me that it was probably only one) back to the train.
The best thing that we co-own, however, is the gun-egg mold. I know, you're jealous (and confused because you don't know what I'm talking about, but you're still jealous). Basically it's a cookie cutter that you can fry an egg in and the egg comes out in the shape of a gun. Everyone wants one, it makes eating fried eggs feel dangerous (and not just to your arteries) and somehow more delicious. It's something I'm proud to own, but what makes it great is that I have someone who's just as excited about it as I am.
That's a really big and important part of the college experience, the roommate experiment. All I did was be completely honest and respect roommate boundaries and it has turned out great.
Now she and I are looking for a yard gnome. Jealous? I know.