The different classes in SCP: Secret Laboratory are aligned in different ways, with some being considered enemies or friends to others.
Alignment and Win Conditions
SCPs work for themselves. They must kill all Foundation Personnel and Class-D. They are neutral to the Chaos Insurgency however. For an SCP victory, all humans, excluding the Chaos Insurgency, must be killed.
For an MTF victory, at least one Scientist must escape and all SCPs, Chaos Insurgents and Class-D must be eliminated. Scientists do not have their own win condition as they share one with the MTF.
Chaos Insurgents work to rescue Class-D personnel and work against the Foundation. It is not necessary to antagonize the SCPs as the Chaos Insurgency however.
For a Class-D victory, at least one Class-D must escape and Foundation personnel must be eliminated. The Chaos Insurgency does not have their own win condition as they share one with Class-D.