From said book:
"Once regarded as mad human wreckage, with the increasing favor of the Emperor Vader has risen in power and influence to become a much-feared military commander. Grand Moff Tarkin was one of the few who recognized Vader's capabilities in spite of his bizarre appearance and eccentric conduct, and as Tarkin's right-hand man Vader attained a new level of respect among the upper echelons of the Imperial military."
Why the hell has no one treated that!?