Tonight’s episode of The Flash delved into Harrison Wells’ backstory and featured some major reveals about the Reverse Flash.

Warning: This post contains major spoilers from The Flash season 1, episode 17, “Tricksters.”

On The Flash season 1, episode 17, “Tricksters,” Mark Hamill reprised his role from the original Flash series as James Jesse, the Trickster. Meanwhile, Barry struggled to work alongside Harrison Wells, having suspicions about his involvement in his mother’s death. Joe and Barry eventually brought Eddie in on the secret of Barry’s identity so he could run interference with Iris and help them investigate Wells.

Meanwhile, flashbacks revealed that Harrison Wells was not the original Reverse Flash. In fact, the real Eobard Thawne, after traveling back in time and killing Nora Allen, discovered he was unable to travel back to the future. In order to get back to his own time, he caused a car accident that killed Tess, Wells’ wife. He then stole Wells’ appearance and killed him in order to expedite the launch of the particle accelerator.

The original Eobard Thawne was played by Matt Letscher, who spoke about taking the role of Eobard Thawne.

Letscher says he was offered the role in December 2014 but was unable to tell anyone outside his family. In offering the role, the Flash producers “basically laid out who the character was, and then they told me that it’s basically who Tom [Cavanagh] has been the entire season,” Letscher explains.

“I’d been watching the show so once I knew that, I was on board. I knew this would be a mindblowing revelation for people. Having worked with Andrew [Kreisberg] and Greg [Berlanti] before, and Tom, everything about the opportunity excited me, so it was an easy sell on their part.”

The role was also pitched as recurring. “I’ll be back this season,” Letscher promises. “It was definitely pitched as something that they would like to develop in some way, beyond this year even, possibly. I’m especially interested to see what it does for Tom and his character on the show — I think it presents a delicious conundrum for fans and for the writers themselves on how they’re going to handle it.”

Letscher adds that he only knows “bare bones” about the future Eobard originates from. “They have a lot of possibilities — if you’re just going from The Flash’s own history as a storyline, you have a lot of different possibilities you can choose from in terms of how you want to develop Eobard Thawne or Professor Zoom or whatever you want to call him. I think they’re still sorting some of that, about how they want to look at him in the future.”

Letscher says that he began researching Eobard Thawne, but early on “Andrew said, ‘You don’t need to worry too much about any of that, because there’s so much there, and so much of it isn’t useful for what we’re doing right in the moment.’ So I did enough to know just how rich the history was for the character, and when it came to actually doing the work it was just, ‘focus on the script, make sure I’m up to date on what the story has been in the season so far, and then devote myself to what’s happening right now.'”

As for joining the series, Letscher has nothing but positive things to say. “[T]o be working with such great actors… Grant [Gustin] has been doing such a good job, he has such a lovely presence, he handles things with aplomb and Tom Cavanagh, who I’ve worked with before and watched his work this year, I feel like he’s done really great work and you just know you’re signing on to quality across the board. As an actor, there’s nothing else you can ask for.”

The Flash returns with new episodes on Tuesday, April 14 at 8:00 p.m. ET on The CW.

What did you think of the Eobard Thawne revelation on ‘The Flash’?