Conversation so far:
why did the band Fall Out Boy have a hiatus in 2010?
During the hiatus, the Fall Out Boy members each pursued individual musical interests.
did Andy Hurley seek treatment for his depression?
Did members of Fall Out Boy work on other things during their break?
Patrick Stump was the only member of the quartet to take on a solo project while Fall Out Boy was on hiatus.
What is one thing Patrick Stump worked on during the hiatus of Fall Out Boy?
Patrick Stump was the only member of the quartet to take on a solo project, recording debut album Soul Punk.
What did other Fall Out Boy band members do?
Pete Wentz formed electronic duo Black Cards with vocalist Bebe Rexha in July 2010.

Question: what's another side project one worked on during hiatus?
Self-contained rewrite: what's another side project one member of Fall Out Boy worked on during hiatus?