From left: Devon Gummersall, Samantha Sloyan and Brandon Keener, and Jennifer Christopher in guest roles in The Pitt . Photo-Illustration: Vulture; Photos: Warrick Page/Max Jennifer Christopher has done dozens and dozens of guest-acting stints on TV shows over the years: The Mentalist , How to Get Away With Murder , The OA . But her experience on The Pitt was unlike any she had before. “I have to be really honest with you, I was afraid of this role,” she says of playing Trish, a shell-shocked