The second season of 13 Reasons Why proved that there was more to Hannah Baker than what she chose to reveal on the tapes. (Spoilers for Season 2 lie ahead.)

Part of what made the first season of the Netflix teen drama so compelling was the way it weaved past and present narratives in the aftermath of Hannah's suicide. Through a series of 13 tapes, Hannah was able to tell her version of events. In Season 2, those on the tapes finally got a chance to tell their stories, which led to some truly shocking reveals — like Hannah's summer fling with Zach Dempsey.

Actor Ross Butler knew the season's big surprise going into Season 2. "I knew what was going to happen with my character, but I didn't know when and how," he told MTV News. "And I also didn't want to tell anyone else, so that when we went to the table read we'd all experience it together. That was fun. At the table read, people were like, [gasp] What!"

In Episode 6 ("The Smile at the End of the Dock"), it's revealed that Zach and Hannah hooked up — multiple times — the summer before junior year. (The summer after Zach stole Hannah's compliments from class; Hannah never mentions his apology or the fling in his tape.) They even lost their virginities to each other. Zach's memories of that summer play out like a teen rom-com, all awkward limbs, nervous laughter, and fluttering hearts.

But their relationship was more than some high school fling; Zach and Hannah had genuine feelings for each other — and they had a lot of fun together. For the actors, it was a reprieve from the melodrama of the rest of the season. "It was a nice little intermission in the middle of the season," Butler said.

"It was great because Kat [Langford] and I have really bonded over the last two years that we've known each other," he added. "We have similar senses of humor, so it made shooting awkward sex scenes a lot more fun and not as awkward. It was an all-around good time. We got to eat ice cream and walk and hold hands."

Butler wasn't the only 13 Reasons Why cast member who knew about Zach and Hannah's "surprising" secret romance, either. "I knew early on," Dylan Minnette said. "That was the one secret that Brian [Yorkey, creator] told me, and I was just immediately super intrigued and also nervous about how Clay would react."

Needless to say, Clay didn't react well to the news. The revelation all but breaks him, as he had spent that summer at his grandparent's house. Clay had always wondered what would have happened between him and Hannah had he stayed. So at first, he's confused — why didn't Hannah mention this in Zach's tape. But when he physically confronts Zach, he's put in his place: "Did she reveal everything in your tape?" (That would be no.)

Clay's reaction was typical Clay, said Minnette, but it was also "out of line," as "Hannah was her own person and could make her own decisions, and Clay just couldn't handle that truth." He added: "All of those elements of truth definitely take a toll on Clay to the point that he doesn't even think he knows what the truth is anymore."

The reveal is Clay's breaking point. Throughout the season, he struggles with the realization that he didn't know Hannah as well as he thought he did, until he ultimately ends up making a devastating decision.

"I knew Clay was going to go through some sort of downward spiral," Minnette said, "but I didn't think he'd be ending up outside of Bryce's house with a gun to his head. That was definitely difficult to shoot, but it makes sense for Clay. He's got a lot of inner demons."

He's also got a major hero complex. If 13 Reasons Why does return for a third season, don't expect Yorkey and the writers to go easy on Clay. In the meantime, let's hope Netflix greenlights a companion series about Zach and Hannah's sweet summer romance. It's what we need after the emotional ups and downs of Season 2.