SmellzYeButt
SmellzYeButt, real name Damon, was Greg's friend, introduced by then girlfriend Shiloh. They worked on many songs and videos together.
Friendship
In February 2011, Greg was recording in a different location than his home and made many videos with a new YouTuber that went by SmellzYeButt. It was later revealed, Greg was living in Canada with then girlfriend, Shiloh, and was introduced to Smellz by her. He and Shiloh had been friends for years, most likely because they both worked in the music industry. Damon is a music producer and Shiloh was a pop singer in Cananda.
Greg and Damon created many videos and songs together.
In a 2015 video, Greg says that when they were friends, Damon invited Greg and Jeffree Star to his music studio, Greg says when they were waiting for Jeffree to get there, he smelled pot and pointed out joints in an ashtray to Damon. Damon told him it was not pot. Greg commented that he is a buzzkill. ($ource)
Drama
After Shiloh and Greg's first major break up, Damon took Greg's side. Shiloh mentions being betrayed by a friend in on of her break up blog posts. (Source) This was most likely Damon. Damon made a vlog where he explained that he took Greg's side after hearing his story. He said what Greg said changed his view of Shiloh. (Video removed)
Demise
For unknown reasons, Greg and Damon stopped working together. In a 2012 live show, when asked if he was still friends with SmellzYeButt, Greg says, "no, I'm not." (Source)
Damon has since deleted all SmellzYeButt and SmellzYeButt2 videos and cut off his association with Onision by removing him from his featured channel lists, but keeping others such as Cyr. His only channel to not have received this treatment was SmellzYeButt3, which may have been overlooked.