Is a Company that's task to, Secure any threats, Rescue anyone or anything at is considered friendly, Protect the people and this world, and to mainly protect Civil's.

The S.R.P.C. also has some allies and some hostiles:

(Allies)
Resistant's (half life 2), Military, O.D.S.T., H.E.C.U., Spec Ops, B.S.E.C., ARC Prison, S.C.P. Foundation, Mercenary's,...

(Neutral)
F.F., Third Echelon,....

(Hostile)
Xen, Flood, Zombies, U.D.R.C., Black Ops, Combine, A.C.E., Chaos Insurgency, E.W.A., The Infected (Underhell),....

Join the S.R.P.C. if you like or participate in it your choice.
Secure, Rescue, Protect, Civil.