Simon Petrikov plays Greg and acts as a co-GM of Steven and the Crystal GMs.
Simon is typically a friendly carefree guy but does have his share of frustrations. One secret frustration lies in a lack of 'dude time' considering his wife is at his regular table, much as he loves that, and how the other members of the table prior to Finn were all women.
Genuinely likes and cares for all three but does have his share of complaints. Phoebe throws off party balance without a second thought, often to the detriment of a campaign however funny it winds up being. Bonnie can get overly devoted to her characters and will often go out of her way to stir up unnecessary drama to build on such. Marceline CAN be too quick to anger and can be a little sensitive to even an imagined insults.
Simultaneously in spite of those complaints, he finds Phoebe hilarious typically, Bonnie is a great help and it's nice having someone more intellectual to hang around, and considers Marceline to be like a daughter.
Can however be prone to anger himself especially when someone won't leave him alone OR messes with any of them. Often prefers to just play a background character or enjoy a role as the DM/Co-DM.