Fitz (Iain De Caestecker) shares his concerns with imaginary Simmons (Elizabeth Henstridge) on Marvel's Agents of S.H.I.E.L.D. episode 2 "Heavy is the Head."

Fitz (Iain De Caestecker) appears to be a little jealous of new agent Alphonso "Mack" MacKenzie (Henry Simmons) on Marvel's Agents of S.H.I.E.L.D. episode 2 "Heavy is the Head."

Fitz (Iain De Caestecker) talks to an imaginary Simmons (Elizabeth Henstridge) on Marvel's Agents of S.H.I.E.L.D. episode 2 "Heavy is the Head."

Alphonso "Mack" MacKenzie is played by Henry Simmons on Marvel's Agents of S.H.I.E.L.D. Season 2.

Alphonso "Mack" MacKenzie (Henry Simmons) meets with Fitz on Marvel's Agents of S.H.I.E.L.D. episode 2 "Heavy is the Head."

Fitz (Iain De Caestecker) struggling with his condition on Marvel's Agents of S.H.I.E.L.D. episode 2 "Heavy is the Head."

Simmons (Elizabeth Henstridge) and Fitz (Iain De Caestecker) in deep thought on Marvel's Agents of S.H.I.E.L.D. episode 2 "Heavy is the Head."

Agent Peggy Carter played by Hayley Atwell, appears in a 1940s-era flashback in the season 2 premiere of Marvel's Agents of S.H.I.E.L.D.

B.J. Britt as Antoine Triplett, Chloe Bennet as Skye, Iain De Caestecker as Agent Leo Fitz, Ming-Na Wen as Agent Melinda May, Clark Gregg as Agent Phil Coulson, Nick Blood as Lance Hunter, Henry Simmons as Alphonso 'Mac' Mackenzie, Elizabeth Henstridge as Agent Jemma Simmons and Brett Dalton as Grant Ward.

Clark Gregg as Director Phil Coulson on Marvel's Agents of S.H.I.E.L.D. Season 2.

Patton Oswalt as Agent Koenig on Marvel's Agents of S.H.I.E.L.D.

Wilmer Calderon as Idaho on Marvel's Agents of S.H.I.E.L.D.