Melissa McCarthy strikes a serious tone in her latest movie "Can You Ever Forgive Me?" -- playing a woman who embellishes literary letters by prominent writers -- and said she fell in love with her character who "wouldn't change for anyone."
"I know it is totally something kind of different from I'm not known for," McCarthy said on "GMA" about the shift from her well-known comedy roles in films like "Bridesmaids." "It was fantastic."
She described how she learned to appreciate the prickly personality.
"I still kind of fall in love with the character, I fall in love with the story," she said. "And the process for me with playing Lee Israel was just finding her quirks and ticks, and there were so many. She was not an easy person by any stretch, but I became really enamored with her early on, and it was really fun to play."
McCarthy said they filmed the movie in an impressively short time frame.
"It sounds like I have gone insane and I'm making up numbers," she said. "We shot it in 28 days in Manhattan which is crazy for a movie."
The dark comedy is based on the true story and best-selling memoir of Lee Israel, a writer living in Manhattan who turns her talents to deception with the help of her friend and sidekick Jack.
"I just love that she was exactly who she was and wouldn't change for anybody," McCarthy reiterated. "She didn't need someone to like her -- she wanted her work acknowledged. And I think that's a really good thing to be reminded of today when I think so many people kind of look to others to reflect how they should feel about themselves."
Her co-star Richard E. Grant, who also appeared on "Good Morning America," said he "buckled" on a daily basis around McCarthy.
"That's not true," McCarthy quipped, "nothing buckles this one."
(MORE: 13 new films, TV shows and more to check out Oct. 14 to 20)"There were some scenes that were really difficult -- and you have to keep your concentration, but for the rest of it -- it became kind of silly," she said.
"Very, very chatty," Grant added.
But in all seriousness, Grant said his sly character Jack had a "love-hate relationship" with Israel.
"He is a con man, so he goes out and he is always making some kind of deal with somebody," Grant said. "Out of desperation, he colludes with Melissa's character. They have this sort of love-hate relationship all the way through."
The movie hits theaters nationwide Oct. 19.