Chapter 1
Stage 1: the baby headcrab is "born" inside the sac of the gonarch. After several minutes/days/months/years/decades of development, it somehow exits the body of the mother and starts its adventure of zombifieing , controlling, and, ultimately, death, to the MAX!
Stage 2: during its second stage of development, the baby headcrab wanders around aimlessly, ultimately ending up in black mesa or staying in their homeworld, xen, While developing vital parts of their system, specifically the beak, which is the part where they latch on to humans.
Stage 3: by this stage all of the vital parts of their system are fully developed, meaning that in this stage, the headcrab latches on to a human victim and starts the transformation of a human from a dead corpse to a headcrab zombie.
Stage 4: now that the headcrab has created a headcrab zombie, they are now capable of getting of food to eat. After a day or two, they go and start injecting steroids/adrenaline/some hormone or drug/body fluids, and then go into
Stage 5: the headcrab zombie is turned into a big, pumped up, adrenaline overdosed, headcrab gonome. The downside is that the headcrab loses bodily fluids, resulting in deflation, a.k.a. "weathering", when the headcrab becomes skinnier and smaller. Thing is, the gonome gets a ranged attack to in which it can shoot acid spores from it's claws. It can then sprint to the victim and claw it with the big claws it has.
Stage 6: the nuke explodes, resulting in death.
