Lyle is the "oiled guru" (127) of the E.T.A.. He spends his time in the weight room of the Academy, and "lives off the sweat of others. Literally" (128). After the players work out, Lyle licks the sweat off them and gives them "some little nugget of fitness-guru wisdom" (128). Although some of the newer residents are afraid of Lyle, he's "like a beloved nut. He's an E.T.A. institution" (128). Lyle is considered to be an excellent listener, and "like all good listeners, he has a way of attending that is at once intense and assuasive: the supplicant feels both nakedly revealed and sheltered, somehow, from all possible judgment" (388). In his discussions with the students, Lyle gives some important bits of advice to LaMont Chu and Ortho "The Darkness" Stice.
Lyle was close to James Incandenza before Incandenza's suicide. The two of them would sit in the weight room "til all hours" (379), Lyle drinking Caffeine Free Diet Coke and Incandenza drinking Wild Turkey. Mario Incandenza would often accompany them. Lyle liked to read Blake to Incandenza in the voices of "various cartoon characters" (379).
Lyle also appears to be able to hover "just a couple mm. above the top of the towel dispenser in the unlit weight room, eyes rolled up white, lips barely moving and making no sound" (700).
Lyle's "wraith" accompanies James Incandenza's wraith to visit Don Gately in the hospital, where Gately opens his eyes to the sight of Lyle "fucking licking Gately's forehead with a rough little tongue" (933). As Gately moves to assault Lyle, Lyle vanishes with the established lightning-quick speed of wraiths.