Succession star Justine Lupe said her character, Willa, being engaged to Connor Roy (Alan Ruck) will be unpredictable in the fourth and final season, premiering Sunday at 9 p.m. EDT on HBO.

Connor is Logan Roy's (Brian Cox) eldest son, and the one Logan keeps out of most company and family business. As the title suggests, Succession is about the drama of who may succeed Logan as CEO of the Waystar Royco media empire.

Logan keeps hanging on to his title, leaving his children, including Kendall (Jeremy Strong), Shiv (Sarah Snook) and Roman (Kieran Culkin), in limbo and jockeying for position.

Connor first brought Willa to visit Logan in the hospital in Season 1, having hired her as a professional escort. Willa then accompanied Connor to a gala and ultimately became Connor's steady girlfriend.

"It's almost like proposal after proposal after proposal," Lupe said. "There've been so many, like 'I love you' and 'Will you be my partner?' and 'Will you date me?'"

Still, committing the rest of her life to Connor was not a frivolous decision for Willa, Lupe said. She said Willa values Connor's money, but she also wants to protect Connor's vulnerability.

As for the money, Lupe said Willa does not know exactly how much of the Roy family billions Connor has. Lupe said Willa knows it is enough to support her personally and professionally as an aspiring actor.

"The money has affected the relationship, and I think she'd be really transparent about that and open about that," Lupe said. "But I don't think she gets into the nitty gritty of how much exactly do you have?"

Connor also wanted to have a partner for his presidential campaign. Even Connor knows he only will have 1% of the vote, but he maintains his campaign just so he can remain in the media as a presidential candidate.

Willa has no ambition to be first lady, Lupe said.

"I think she just wants to support Connor," she said. "I think whatever ride he wants to go on, she'll be there for him. It's more just be standing by him and being a good partner."

"Scripts kept on changing, and finally I was like, 'Wait, am I not booted? Am I sticking around?' which was awesome," Lupe said. "I didn't really question it."

Succession's original plan for Willa was three episodes. Even as Lupe returned for subsequent episodes and seasons, she said she never took it for granted that Willa would stay with Connor.

"It was also like a TBD," Lupe said. "I've been feeling like maybe Willa could be booted at any point in this whole process. Their relationship is so strange and fragile."

Now that Succession creator Jesse Armstrong announced that the fourth season will be the final one, Willa has made it to the end. Lupe said the cast found out near the season finale that it would be the series finale.

"It's devastating," Lupe said. "As heartbreaking as this is personally, I think I trust them to have made the right decision."

Lupe is filming another project that she said she cannot announce. The actor said that as difficult as saying goodbye to Succession was for her, a supporting cast member, she empathized with the lead ensemble.

"The last days of filming were super intense," Lupe said. "I woke up the day after I wrapped with what felt like a hangover just from crying so hard."

Succession airs Sundays at 9 p.m. EDT on HBO.