SPOILER ALERT: The story contains details about tonight episode of Suits.

USA Network’s veteran drama Suits aired its 100th episode tonight, directed by star Patrick J. Adams. It was a very eventful episode that closed the prisoner abuse case Mike had been secretly working on, with the bad guys punished and Alex relieved from the blackmail threat of forged evidence. With the legal case wrapped up, the episode stirred up old flames: Donna’s ex, Mark Meadows (guest star Jay Harrington), introduced in the previous episode, and Louis’ former love Sheila (Rachael Harris). Both Donna and Louis received indecent proposals — Mark, who turned out to be unhappily married, asked Donna to spend the night with him at a hotel, while Sheila, on the eve of her wedding, offered Louis the same, at the same hotel. The episode ended with both Donna and Louis going to the hotel and knocking on the respective doors — with Donna backing out as she sees Mark while Louis walks in — all the while Harvey celebrates a two-month anniversary with Paula with a romantic dinner. In an interview with Deadline, Suits creator/showrunner Aaron Korsh talks about the surprising propositions and their outcome, the future of the Donna-Harvey-Paula triangle and Louis’ relationship with Sheila. Korsh also teases what is to come in the last two episodes of the show’s 10-episode summer sub-season: who will be back (hint, the list includes Jessica), what new addition is planned (hint: it’s not a good person), and which two lawyers will be teaming on a case for the first time (hint: they are related).

DEADLINE: Donna changed her mind on sleeping with Mark at the last moment. Was the alternative, of her going through with it, ever considered?

KORSH: I don’t recall seriously considering her going through with it but I imagine, whenever we have a situation that we are at least going to explore all possibilities by talking about that.

Photo by: Shane Mahood/USA Network

DEADLINE: Jay Harrington had been booked for a two-episode arc, which ended tonight. Is he done or may we see Mark again?

KORSH: We are still formulating Mark. I’ve always liked Jay as an actor, I think he did an outstanding job with the two-episode run, and I think the two of them (Sarah Rafferty, Harrington) have good chemistry. I feel like as far as the character of Mark Meadows goes, he is a flawed guy to be completing doing what he’s doing. Donna has been the one for him and it looks like his marriage is likely to end anyway. He’s not going about it in the right way but he’s not evil. In my mind, the door is open for Mark to come back, but we haven’t gotten that far yet. I don’t know for sure but I liked their chemistry and the story with him.

DEADLINE: Would the Donna-Harvey-Paula triangle continue even after Harvey and Paula appear to be in a good place in their relationship?

KORSH: I think Harvey and Donna’s history and feelings are so strong and, especially coming off such a disappointment for Donna at the end of Episode 8, that triangle will probably continue to exist. If Paula is in the picture, there is going to be some tension there, and we are definitely going to play some of that in 9 and 10.

DEADLINE: What about Louis and Sheila? Was the hookup a one-time thing or will Sheila stay in the picture?

KORSH: Rachael Harris was a series regular on the first show that I ever worked as a writer on (Notes From the Underbelly), and I’ve always loved her as an actress, also Peter Cambor who plays Nathan at the clinic. There is a funny story — we were discussing Louis and Sheila. We have a new editor this year, and the editor said, it’s always been Sheila for Louis, it wasn’t really Tara. When he is talking about closure with Tara, he really means Sheila. This is just an editor coming from outside. We already had this story in mind, so this was an interesting dovetail into that.

I think that Sheila will be destined to play a significant role throughout the Suits life. We haven’t broken the back six yet so I can’t be sure, but I don’t suspect this would be a one time thing, and certainly we play the ramifications of what Louis does in the future episodes.

DEADLINE: What else can you tease about the tangled relationships, the Donna-Harvey-Paula triangle and Louis’ fling with bride-to-be Sheila, in the last two episodes of the summer run?

KORSH: In the tangled relationship area, I feel we have a very big thing coming at the end of 10 in one of those relationships that people may or may not see coming.

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DEADLINE: Any other hints what’s to come in Episodes 9 and 10?

KORSH: The things that befall us in 9 and 10 in large part are things that were laid in during the first six seasons, but in large part in the first 8-9 episodes this season. A lot of things will come back to haunt us. In addition to that, we’ve got a new villain who would come out of the woodwork. Plus, we’ll see Gretchen (played by Aloma Wright), we’ll see Lipschitz (played by Ray Proscia). Gretchen has a very strong episode in 9, maybe the best ever.

DEADLINE: Will Jessica be back in the last two episodes?

KORSH: Yes, Jessica is in at least in one of them.

DEADLINE: Tonight’s episode wrapped the big prison case story arc of the season so far. Was that intentional to coincide with the series’ 100th episode?

KORSH: No. What often happens in the first 10 is, we end up getting to the conclusion (of a big arc) in episode eight or nine. As we were breaking the story, it just looked like hey, this should be the episode where we end things, so it was a happy circumstance but it wasn’t designed this way because it was the 100th.

DEADLINE: With the prison case closed, will you open a new legal case in the last two episodes?

KORSH: We have two major mini-story arcs for 9 and 10. In nine, Louis is working on a case with an associate, Harvey and Mike are working a case together that would last two episodes and would involve other people in the firm. And Rachel and her father are going to be working together on a case in the last two episodes.