In "The End in the End", both Cam and Arastoo make it out of the Jeffersonian safely before the explosion.
After Brennan can't remember the clue she found to Mark Kovac's location in Fred Walden's bones nor can she analyze them due to her head injury, Arastoo joins Clark Edison, Wendell Bray, Daisy Wick and Jessica Warren in performing an analysis on their own to find the clue.
After a rousing speech from Hodgins, the intern team is able to use what Brennan has taught them to find the clue and through it, locate Kovac.
Afterwards, Cam reveals to Hodgins and Brennan that she and Arastoo are taking a leave of absence during which Hodgins will be in charge in order to travel to Mississippi and adopt three foster children there.
He made a speech on the 9/11 terrorists' religion and his own while investigating the death of Tim Murphy. In the same episode, Arastoo admits to Hodgins that he is a political exile and can never go home again.
In 1997 while in his first year of university, Arastoo had published his poems on an underground press, believing the Khatami regime to be more accepting of them.
When asked if she noticed anything strange about Arastoo's accent, Brennan says she thought it was odd that an Iranian would speak English with a Jordanian accent, but she felt that was his business. Iranians speak Persian, whereas Iraqis speak Arabic, although it is possible he is trilingual.
Expecting others would find it odd that he is both a scientist and very religious (a suspicion his co-workers later confirmed), Vaziri decides to put on a false accent to sound "fresh off the boat" and thus make his religious devotion seem like an irrelevant byproduct of his heritage.
In Beautiful Day in the Neighborhood, he slips up, and his secret is revealed first to Dr.
Saroyan, and then to the rest of the team (and the audience). In The Devil in the Details, Vaziri says he served as a military translator in Iraq, where he killed an insurgent while defending his life after surviving an IED. What is not explained is why Vaziri, from Iran, would serve as an interpreter in Iraq.
He returns in "The Doom in the Boom" when he heard that Cam was near an explosion at a crime scene.
He was offered a position in Berlin, but after realizing that it was a mistake for him to leave Cam, he declines as was revealed in "The Monster in the Closet".