Umber was a member of the Neverseen, and an extremely powerful Shade vital to Lady Gisela's plans. She kept her real name hidden along with her physical appearance with a Neverseen cloak. Keefe stated that Umber and Trix seemed like the two frequently worked together.
Umber's voice is described as being soft and raspy, like wisps of smoke. She is one of the few Shades who not only knows how to use shadowflux, but have trained for years with it. Umber puts this sixth element to great use, creating shadowflux spears to launch at her enemies.
Keefe was introduced to both Umber and Trix so he wouldn't be surprised about their involvement in Wylie's kidnapping. Neither Keefe nor Umber liked each other.
Umber was one of the Neverseen members who ambushed Sophie, Fitz, Sandor, and Grizel at the desert training camp. Determined to find the location of Wylie Endal, Gethen ordered Umber to start torturing them with Shadowflux. Umber happily obliged, mangling Sophie's right hand and filling both her head and hand with echoes, as well as Fitz's right leg and heart. When Dex, Lovise, and Wylie arrived as backup, Umber flung shadows at them, but could not hit them. After Ruy's force field was destroyed by Wylie's full spectrum blast, the three Neverseen members fled.
Umber showed up once again in Everglen with Gethen, Vespera, and Ruy. When they arrived at the hive, Umber used shadows to open the door, despite the frantic pleas by the troll Tarina. After Umber saw the newborn trolls for herself, she thought better and tried to close the door again, but she wasn't fast enough. The newborns knocked the heavy metal door of its hinges, causing it to fall on Umber and mortally injure her. Ruy attempted to cover her with a force field, but he was quickly infected by Tam's Shadowflux, so the three remaining Neverseen members fled, leaving Umber behind to die. Her body was later recovered after the battle, but it was so mangled beyond recognition that no one could identify it.
At the end of the book, Lady Gisela forces Tam to join the Neverseen by threatening his sister and the new alicorn babies. This was because the ability to control Shadowflux plays a key part in Gisela's plans.
According to Tam Song's claim when talking telepathically with Sophie Foster, he had to spent a lot of his time with the Neverseen training according to Umber's notes, with a little understanding of what exactly he was doing. Those notes may or may not have to do with what Tam was finally forced to perform at the scene in Loamnore.
Nothing is known about Umber's physical appearance, other than the fact that she has an unknown shade of blue eyes. Most Shades seem to have dark hair, possibly including her. She used shadowflux to transform her fingernails into long claws.
Umber had a sadistic personality, and reveled in other people's pain. Because she trained for years with shadowflux, she allowed it to infect her.
Compared to the rest of the Neverseen, from what little we got of her, she appears to be sarcastic, impatient, and eager for a competitive fight.
Trix (ally/possible significant other) - while infiltrating the Neverseen, Keefe told Sophie that he got the feeling Umber and Trix worked more closely together than some of the other members did.
“Had enough? Or shall I keep going? There are still plenty of little bones left -- it's one of my favorite things about the hand.”