[6] Raven's faction began expanding at Return of the Funker when Richards introduced The Broad Street Bullies (Johnny Hotbody and Tony Stetson) as the newest member of the group and the four brawled with Dreamer.

It turned out to be a ruse as McGillicutty blinded him with a hair spray and Richards attacked her, allowing Raven to defeat him.

Pitbulls would also compete at the event, challenging Public Enemy (Johnny Grunge and Rocco Rock) for the World Tag Team Championship in a losing effort.

Later at the event, Pitbulls received a rematch for the World Tag Team Championship against Public Enemy in a dog collar match but failed to win the titles.

Raven broke up the fight by taking them backstage, distracting Pitbulls and causing them to lose once again in similar fashion.

At Heat Wave, Raven and Richards retained the World Tag Team Championship against Don E. Allen and Tony Stetson by getting counted out after leaving the ring to break up a brawl between Francine and Beulah.

Later at the event, Raven and Richards lost the World Tag Team Championship to The Pitbulls in a two out of three falls match after Dreamer and 9-1-1 thwarted interferences by Dudley Brothers and attacked crooked referee Bill Alfonso, leading Commissioner Tod Gordon to count the pinfall.

At South Philly Jam, Cactus Jack defeated the debuting El Puerto Riqueño after the latter refused to forfeit the match.

However, at the same event, Raven and Richards lost the titles to Public Enemy in a three-way match, also involving The Gangstas (Mustafa Saed and New Jack).

Later at the event, Richards introduced the debuting The Blue Meanie as his sidekick and defeated Riqueño, while Raven and Jack lost a match to Dreamer and Terry Funk.

Later in the night, Raven and Richards teamed with The Heavenly Bodies (Jimmy Del Ray and Tom Prichard) and The Eliminators (Kronus and Saturn) to take on Dreamer, Pitbulls and Public Enemy in an Ultimate Jeopardy match, where a stipulation would be applied on the participant who was pinned or submitted.

Dreamer attacked Richards but was assaulted by Raven's team as Public Enemy and Pitbulls had been handcuffed to the ring apron during the match.

The Sandman eventually made the save by attacking Raven and his allies with a Singapore cane, forcing them to retreat.

On the first night of Big Ass Extreme Bash, Jack lost a match to Chris Jericho while Raven retained the title against Sandman.

Unlike other factions in WCW at the time, the group (though popular) met with limited success and lost most of their matches.

It was first put together in August 1999 while Raven was in WCW and saw him teaming up with Vampiro and the Insane Clown Posse (ICP) (Violent J and Shaggy 2 Dope).

When Raven quit WCW and went back to ECW a month after the group's inception, Vampiro and ICP stayed together under the moniker the Dark Carnival and continued without him.

Members included: When Raven joined Total Nonstop Action Wrestling (TNA), he formed a new version of the Flock, this time calling them The Gathering.

The original Gathering members were Julio Dinero and Alexis Laree, with CM Punk joining the group soon after its inception.

Raven disappeared from TNA, while Punk and Dinero joined up with longtime Raven-enemy James Mitchell and continued to wrestle under the Gathering tag team name.

When wrestling in singles competition, members often took the role of jobbers to more established stars such as Kurt Angle, Sting or Jerry Lynn.

Serotonin picked up their first official win at Against All Odds, defeating the team of Sonjay Dutt and Jay Lethal following interference from Maverick Matt.

On the March 8, 2007 episode of Impact!, it was announced that Raven had changed their names: renaming Kazarian to Kaz, Maverick Matt to Martyr, and Johnny Devine to Havok.

Serotonin retaliated to this, distracting and therefore costing Kaz in a match against Chris Sabin on the March 31, 2007 episode of Impact!.

On the June 21, 2007 episode of Impact!, Kaz turned on Serotonin by costing Raven a match against Chris Harris.

On the November 15 episode of Impact!, Havok was revealed to be Team 3D's X Division traitor and reverting to his Johnny Devine ring name, effectively ending Serotonin.

In the summer of 2022, segments would air showing various members of the MLW roster laid out with a calling card on their body.