Brad has joined alot of school clubs, including pre-pre-med club in order to look good for his college applications. He joins the safety patrol shortly after Wayne leaves, and thus becomes Fillmore's temporary partner. When Ingrid arrives Parnassus becomes threatened by Ingrid's sucess. He does a background check on her and uses it to his advantage by framing her for a stink bomb. To add to his luck, Ingrid wanted to be expelled from X due to not fitting in.
Fillmore dismisses Parnassus's theory that Ingrid set off the stink bomb and convinces Ingrid to find the real culprit. Parnassus tries to frame Ingrid again by buying more ingredients to make a stink bomb and even dressing up like her to make her even more gulity, however Ingrid and Fillmore catch him in the act. He destroys the hard evidence by setting off the stink bomb.
Parnassus makes his friend take the blame for his actions and he gets off the hook and leaves the safety patrol, claiming that their feud ended in a tie.
Parnassus does not make another appearance after this. in "Test of the Tested" Folsom holds a meeting for the smartest children to prepare them for retaking their test, which Parnassus doesn't attend. It can be applied that Parnassus wither left X or was expelled after the incident.