Tanner's a Glow that has the ability to interfere with airline navigation systems. He can do this from the ground.
Tanner's electrical powers allow him to interfere with airplanes' electrical navigation systems and cause them to malfunction and crash. His powers are so advanced that he can do this from the ground. Hatch used this to blackmail airlines for money. Prior to taking down the British airline jets in The Prisoner of Cell 25, he had crashed more than two dozen private jets.
Tanner was found by the Elgen in the same week as fellow electric McKenna. He was blackmailed into following Hatch by watching his younger brother be electrocuted by Zeus. At some point between The Prisoner of Cell 25 and Rise of the Elgen, Tanner has a nervous breakdown of guilt, causing him to attempt to take his own life. He is brought to the Amazon compound with the rest of the Glows, and on the way attempts to sacrifice himself and take out Hatch by bringing down the jet they were flying in, but is stopped by Torstyn. He is put under RESAT treatment at the compound, but is rescued by The Electroclan and joins them. He is last noted in Rise of the Elgen saving Michael from Elgen helicopters.
The rest of the Electroclan meets up with Tanner and Grace at Timepiece Ranch (the ranch the Voice had been keeping them at in the beginning of the book). He is noticeably happier, and being medicated for his mental health. At the end of the book the ranch is destroyed, but Tanner and the rest of the group leave before it is attacked. The voice tells Michael that there were no survivors at the ranch.
Tanner briefly makes an appearance when Michael and the Electroclan arrive at the other safe place. He tells Michael that he can't understand why Nichelle is with them, and Michael tells him that Dr. Hatch made all of them do things that they regret. He adds, "you can understand that". Tanner is briefly shocked by this, but then agrees with Michael that forgiveness is part of healing. Michael tells him to let it go and Tanner thanks him for the advice.
Fall of Hades
Tanner participates in the mission to rescue Welch and the rest of the Glows (Quentin, Torstyn, Tara), and steal the Joule. During the mission he was killed by a mortar blast while in the Hades Prison.
Little is known about Tanner's personality before his breakdown. When Michael and the Electroclan attempt to rescue him, he seems to have accepted his fate, saying that he deserves to die in the rat bowl for the murders he committed for the Elgen.
In Hunt for Jade Dragon, Tanner seems much more at peace, even thanking Michael for saving him. By Storm of Lightning, he seems to have recovered (for the most part) from his mental trauma, though he most likely still harbors feelings of guilt and regret for his actions.Tanner is otherwise very suave and charming and likes cars, as well as dark books, as shown in Hunt for Jade Dragon. Deep down, however, he's mentally disturbed from the remorse, horror, and nightmares he experiences from doing Hatch's dirty work. What Tanner really needs is love, attention and more notice than he's getting.
Tanner had a mental breakdown between The Prisoner of Cell 25 and Rise of the Elgen. This was caused by pent up guilt from the numerous murders he committed for the Elgen. He was separated from the other Elgen electrics, and kept heavily sedated when not being treated. It is possible he is completely mentally disturbed, considering Taylor breaks down crying when she gets a glimpse inside his mind.