In a new interview with The Guardian, Hendricks says that her role on the hit show elicited a dearth of enthusiasm from the very people who were supposed to be in charge of her career.
"[My agency] said, 'It's a period piece, it's never going to go anywhere. We need you to make money and this isn't going to make money.' They ended up dropping me."
Hendricks and her manager both loved the role of Joan, though: After the actress scored small parts in ER and Without a Trace, they recognized the role's – and the show's – potential. "I had been on several shows that were meant to be the big ones, that would go on forever, and they didn't. So there was no sure bet and I'd already taken a chance on them, and I felt, why not do the one you're in love with and take a chance on that?"
Hendricks also touches on her time in high school – something that's already earned a lot of online chatter (mostly in the form of pictures showing her goth wardrobe).
"My parents would say, 'You're just alienating everyone. You'll never make any friends looking like that.' And I would say, 'I don't want those people to be my friends. I'm never going to be friends with the people who beat up a kid while everyone is cheering them on. I hate them.' "
Hendricks is currently starring opposite the late Philip Seymour Hoffman in God's Pocket, which is directed by her Mad Men costar John Slattery.
"I keep thinking I'm going to see him again," she says of Hoffman. "I guess, when I watch the film now, I feel like it's a celebration of him. I feel lucky to have gotten to work with him. I feel grateful and I feel sad."
God's Pocket was released in May. Mad Men's final seven-episode run begins in 2015.