[s1e4] The World In The Walls →

When the real Penny eventually enters the dream, he is furious at the "racist" orderly caricature Quentin's mind created.

The entire scenario is a Scarlatti Web spell cast by Marina and Julia to distract Dean Fogg. Marina’s goal is to lower Brakebills' wards so she can break in and steal her erased memories. [S1E4] The World in the Walls

After helping Quentin wake up, Julia is betrayed by Marina, who burns her hedge witch "stars" off her skin and banishes her from the coven. When the real Penny eventually enters the dream,

The Magicians: Season 1, Episode 4 - "The World in the Walls" Julia is betrayed by Marina