Facebook Timeline Friends Question...?

[☼ Roulette ☼]

Okay, so on the Timeline on Facebook near the top it has a small box with 6 friends and then a little further down there is a bigger box with 8 friends. I have 914 friends, but always the same 10 or 15 people seem to show up ever since I got Timeline for as long as I can remember. I'm really good friends with every single one of the people that show up and talk to them on a regular basis. I do interact with them over Facebook to creep or occasionally like a picture or status, some more than others though. My question is, how does Facebook decide which people will go on there? How do they know I'm good friends with those people? I've heard that it's the people that have recently creeped on you. Is this true? Since I have almost 1,000 friends, if it truly was random there would be people in the boxes that I wouldn't talk to a lot or don't know, or the names would constantly change. But they don't. So is it random? Or does it tell you something else?