He was on the team of scammers attempting to steal Rick's recipe for concentrated dark matter. They captured Rick and put him in a simulation, inside of a simulation, inside of another simulation. Stu was the Zigerion who discovered Jerry's presence in the simulation and alerted Prince Nebulon. Like the rest of the Zigerions aboard the spacecraft, he was killed when the "formula" they believe they scammed from Rick caused a massive explosion and destroyed their entire ship.
While he only appeared in the episode briefly, Stu seemed more serious and professional than many of his colleagues. He didn't whine or joke about Rick and Morty's nudity, instead remaining focused on his job.
Stu was also intelligent and efficient, being the first to realize a second human is in the simulation and quickly identifying him as Rick's son-in-law, Jerry Smith.
- In the episode Close Rick-Counters of the Rick Kind, there was a picture of Stu on the wall of Rick's bedroom.