No one is an island. Everyone meets others, forms connections with them. There are bonds of friendship, bonds of antagonism. People often influence one another more than they realize.
Ravelers look at the bonds between people, and can manipulate those bonds. Through the ravels that connect a person to others, he can either give them support and strength, or draw their attentions and energies into the depths of corruption. In battle, a friend is worth more than just another sword by your side; the two of you transfer strength, willpower, and skill to one another, whether you are aware of this or not.
Spending time in contact with someone, interacting with them, builds up a complex series of ravels between you. They interact with each other, and with the ravels that connect you to other people. It would not be far off the mark to say that entire civilizations are vast networks of ravels, and often behave similarly to single organisms.
Being cut off from everyone is not only disheartening, but dangerous. The abrupt severing of many of the ravels that connect someone to the world about him can be deadly, and more often leaves the person an empty shell, without will or power to act.
I take it that the person you just spoke with at the other table told you who I was, because you've just gained a ravel of recognition. Ah, yes, now it is growing and solidifying. Definitely me. Well, what can I do for you?
No, that's not really much of a trick. It just takes practice to recognize the ravels. Besides, even someone who can't could have figured out you were looking for me just by watching your face. What's hard is seeing your relationship with the man you just talked to, since it's not strong and you aren't interacting at the moment. Even harder is seeing the ravels connecting you to people who aren't even in this room. Distance seems to stretch the ravels thin, and many of the clues that help us to understand them come from watching the people they connect to.
Can I alter the ravels? Not as much as you might think. Creating or destroying a ravel, for example, is virtually impossible. Changing the intensity of a ravel more than a little is very difficult. Changing the relationship between two ravels, or altering the mode of operation of a ravel, are easier. That's what ravelers usually do.
It's easiest when you have a large group of people who all know each other fairly well in the same place at the same time; that's when you can really do something. The really skilled ravelers can weave together the ravels connecting a group of people in complex patterns in such away that the patterns emerge visibly, and seem almost to be a separate entity from the rest of the group. Of course, it's really just a manifestation of the connections between everyone in the group, not an independent entity at all. Then again, I suppose no one else in the group is really independent of the others, either . . .