There is a Reflex Injector found in every mission in FEAR 2: Project Origin, except the first one.

In FEAR 2, players take on the role of Michael Becket, a Delta Force operative who has been genetically enhanced to have improved reflexes and agility. These alterations enable him to temporarily move faster than his enemies, a sort of bullet time. Entering this mode uses up energy, which must be recharged before it can be used again. And this is where Reflex Injectors come in. These function like the hearts in The Legend of Zelda. Using one will permanently increase the reflex meter on the HUD, making it eventually be composed of two bars instead of just one.

The story of FEAR 2: Project Origin begins about 30 minutes before the end of the first game. Developer Monolith Productions used player feedback about the original game to fine tune the sequel. In an interview, associate producer Eric Studer stated, "We've gone to great lengths to ensure [the story] resonates with players more than it did in the first game."1up.com: F.E.A.R. 2 Project Origin Preview (November 13, 2008) The environments and enemies encountered in the game are much more varied this time around. A new graphics engine, improved enemy AI and solid sound effects combine to give FEAR 2 an overall creepy feel.1up.com: F.E.A.R. 2: Project Origin Preview (December 22, 2008)