Demo's master is in fact, Raocow himselfLook at the way he talks, and the fact it was Raocow who came up with the whole vegetable thing.
Demo is from Gensokyo.Before fighting Rumia, she claims that there's something familiar behind the boss door.
Demo is much more sinister than she seems.It is a fact that everybody on talkhaus is Raocow (Except for the moderators). It is also a fact that Raocow is Demo's fursona. Ergo, everybody on talkhaus who contributed to the games is Demo's sockpuppet. Now just what had our cycloptic minion in mind when making the games? Is she trying to shape the world according to her will? Is she trying to get a monopoly of the world's magic vegetables? What if the various avatars in the developers' rooms are real people whom she has kidnapped, trapped inside the games, and then replaced? Why is Iris much less useful than she is? Clearly she's planning to somehow destroy the entire Universe for some unfathomable reason (And the Universe itself has tried to kill her just to prevent that from happening). That being said, I completely support her in her endeavor and hope there will be a suitably epic boss fight at the end of her quest.