Simmons becomes infected with an alien virus after exposing herself to a group of people that have come into contact with a Chitauri helmet.
Did You Know?
Skye mentions The Dude from the Big Lebowski (1998) who is played by Jeff Bridges. Jeff Bridges also played Obadiah Stane/Iron Monger in Iron Man (2008) which is part of the same universe as Agents of Shield. See more
When Simmons shows Coulson the "brain cells", they clearly lack axons/dendrites, which are branchings from the cell walls that make neurons easily identifiable. Brain cells normally use these branches to produce tiny electrical impulses. The cells shown look like red blood cells. See more
Fitz, I don't know what you think you're doing, but...
I'm doing what we always do. We're gonna fix this. Together.
References The Big Lebowski
Agents of S.H.I.E.L.D. Theme Song
Written by Bear McCreary See more