Citizen

Citizens are humans living under Combine rule, after the Seven Hour War and subsequent Combine occupation. The term "Citizen" refers specifically to a human living under Combine rule in a city, as opposed to a rebel or refugee. Over the course of the Half-Life 2 storyline, vast swathes of the citizen population ultimately come to join the growing resistance to overthrow their interdimensional overlords and restore Earth's freedom.

History
However, many of Citizens were safe in the resistance base alongside with resistance rebels.

Idle

 * "I hope we had a better idea for this time."
 * "Oh, this is hopeless... How we supposed going to do?"
 * "Sometimes, I dreamed about cheese."
 * "Should we be...uh...doing something?"

When Using Weapon

 * "Alright, let's do this!"
 * "Time to pay for that."
 * "Let's go!"

When Spotting Enemy

 * "Here they come!"
 * "Oh shit!"
 * "RUN FOR YOUR LIFE!"
 * "Holy CRAP, HELP!!"
 * "Oh my god!"
 * "GET THE HELL, OUT OF HERE!!!"

When Spotting Strider

 * "STRIDER!!!"
 * "RUUUUUUUUN!!!"

When Spotting Combine Overwatch Soldiers

 * "Combine!"
 * "Soldiers incoming!"
 * "Watch out!"