the Steeply–Poutrincourt colloquy: the part of Hal that leaves and hovers
Hal remembers points, senses trends in a match. Wayne doesn’t. Hal’s susceptible to fluctuations. Discouragement. Set-long lapses in concentration. [...] Some days you can almost see Hal like flit in and out of a match, like some part of him leaves and hovers and then comes back.
Context
The specific liability inside Hal's genius. He "remembers points, senses trends," which means he's "susceptible to fluctuations. Discouragement. Set-long lapses in concentration." At its worst it's almost visible — "some part of him leaves and hovers and then comes back," the body playing on autopilot while whatever runs it drifts off. The instrument keeps swinging; the presence that's supposed to inhabit it comes and goes.