With the release of Dragon's Kin by Todd McCaffrey, we have learned a lot about watch-whers. Apparently they're much more intelligent than they're given credit for and they share certain abilities with dragons. They can go between, they can fly (which we might have inferred from the clipped wings of modern Ruatha Hold's watch-wher), and they can bond with humans.
As we know, watch-whers are the result of experiments by geneticist Kitty Ping's daughter, Wind Blossom. Compared to the draconic model, whers are stunted and ugly. They grow about the size of big runnerbeasts and have only two claws per foot. They are near-sighted, territorial, and anti-social, but they make up for it with keen senses of hearing and smell, speed, and use as guardians during the night, when they see best.
Like dragons, watch-whers have smooth hide and come in five colors: gold, bronze, brown, blue, and green. The golds lay smallish clutches of wrinkly, leathery eggs in a dark, secluded location. To get an egg, one must first make an arrangement with the gold's bonded human. The rest is up to the would-be wherhandler. Bonded watch-whers aren't apparently hostile until you prove yourself to be an enemy, which means you may approach the clutch with caution. If the gold mother decides she approves of you, she will allow you to select an egg and leave the den.
Once you have a watch-wher egg, bonding is more or less guaranteed. The egg must be provided an environment similar to a dark, warm cave. Any color watch-wher may bond with a male or female. When the egg hatches, the would-be wherhandler must be there to give the hatchling its first meal and allow it to "blood" them. The baby watch-wher sinks its needle-like teeth into the first available appendage, thereby getting a taste and feel for its human. Once that is done, watch-wher and human are bonded.
Watch-whers do not automatically know their names the way dragons do, but they do choose one in time. The human of the pair learns it by intuition and a little guess-work. A watch-wher's name always ends in "sk," usually preceded by part of its bond's name. The bond between human and wher isn't necessarily as close as that between human and dragon. In the case of a watch-wher, the more the wher's name resembles the human's, the closer the bond. For example, Danil's brown watch-wher's name is Dask. They are good partners, but perhaps not the ideal match. Dask might have been Danisk. A watch-wher bound to a major Hold, however, takes a name based on the Hold's: e.g., Lemosk.
Communicating with a watch-wher is a bit tricky until you get the hang of it. Watch-whers see heat rather than light, which is why day is so distressing for them. The sun's heat lights the air up like white fire. Given that this is the case, presumably a watch-wher would be happy to be out in daytime during a northern winter and not at all pleased to live in a southern climate at any time of year, but this is mere speculation and beside the point. To communicate with a watch-wher, the wherhandler must understand the way his partner sees the world. In Dragon's Kin, the characters accomplished this by shutting their eyes and observing the colors on the insides of their eyelids while looking first at a fire, then away. Try it. Find a bright light, close your eyes, and face it. Now turn slowly away. Notice things going from white to red to violet? The hottest things are white and the coolest black, with the entire light spectrum in between. That is roughly how a watch-wher sees heat—a wher's vision is much more acute within short distances.
Once the wherhandler understands that, the pair becomes that much more effective. If you learn the heat pattern for a location, you can send it to your watch-wher and ask him to go between to that place. With enough experience, you could probably even paint a good image of a place you've never been. A full-grown wher can carry one human on his back and get off the ground, but apparently just being in contact with a watch-wher allows him to take you along while going between. They don't seem to need to be in the air, like dragons. Watch-whers can also talk to dragons, and with training they can learn to communicate with humans by way of sound. Camp Natalon's brown Dask knew sounds for "fast," "bad air," and many more.
Watch-whers live longer than humans do. Uniquely, they do not go between when their bonds die and, furthermore, they may bond anew. Usually (but not necessarily) this occurs within a family, since the watch-wher is already familiar with some aspect of the blood. Presumably, Ruatha Hold's watch-wher was blooded to Lessa's father and then to her before Fax invaded, hence her close relationship with it. She might have made much of that bond, had watch-wher lore not become sadly neglected (along with harpers in general, more's the pity).
Fortunately, it has now been recovered. Hopefully a watch-wher and wherhandler will come to be seen as strong, functioning, respected members of every Pernese hold.
"Essay on Watch-whers" by Neshomeh, 2005-06