Headcrabs!

[Combine 017]

Damn. Alright, time to make some awesome feasible BS so everything turns out positive.

The poison headcrabs are just lazy, that's why they choose fat people.

Zombines can run because the only headcrabs to jump on a Combine soldier are slightly smarter than the average headcrab.

The fast headcrabs are to weak to get through a Combines helmet and Combines aren't fat so the poison headcrabs don't grab onto them, they just bite at them.

Yes the civilians wear white undershirts, and none of them have a blue jacket on because they were in such a panic that a headcrab was getting them that they had to tear off their jacket. Or a more likely reason, it got torn up and fell off during the zombie mutation.

Resistance members haven't really been near any place that has headcrabs. Maybe somewhere else that the Freeman has yet to visit. And if a resistance guy got headcrabed then the other members he was with probably shot him to put him out of his misery.

I have a question to. Why aren't there any Zombine Elites, that would look cool.