After he and the gang escape, Thrax sets up a meeting at the Zit to gather new crew members for the final stage of his plan. After killing the current mob boss, Thrax and his new gang go to the sinus dam to cause a runny nose.

He then ventures to the left armpit to build a gang to help him take down Frank. He then sets a saliva boat on fire and causes a sore throat. The first thing he does is destroy the cells that found him in order to eliminate witnesses, despite the fact that Artie's coworker surrendered. Thrax arrives in Frank on an egg that he dropped on the ground at the zoo. He was able to use his prior experience to near-lethal effect, making it appear that he was a common cold-hearted virus until he attacked Frank's hypothalamus. He's knowledgeable about how to take down a human being, possibly implying that he killed more than the three people mentioned in the movie. Thrax also shown his intelligent and manipulative nature. Thrax also has no problem deceiving and even killing his own allies.

He is shown to lose his temper when things don't go as he'd hoped. Thrax is extremely disgusting, cold, sadistic, intimidating, callous, murderous, self-centered, destructive, pernicious, and deadly. Interestingly, his original name is used on the movie summary of the Swedish DVD back cover of Osmosis Jones. Thrax's original design had much more resemblance to a virus.

What substance kills thrax