Pennywise haunts the dreams of It actor Bill Skarsgård 

Even when Bill Skarsgård was done playing Pennywise, the shapeshifting killer clown was not finished with him.

The actor who portrayed the bloodthirsty being in Stephen King’s

says that even after he completed filming the movie, which debuts on Blu-ray today, it was hard to get the creature out of his head.

“I liken every character that I do to a relationship that you’re in,” Skarsgård tells EW. “Pennywise and Bill go into this sort of relationship together, and I’m trying to figure out who he is and I have to devote so much time and effort to this other person – or thing, in this case – and that goes on for months.”

After living in Pennywise’s shell for so long, it began to warp his attitude in ways even he couldn’t see. “It’s just like being in a very destructive relationship,” Skarsgård said. “People don’t really realize it until they’re out of it. All your friends go, ‘You need to dump this piece of sh—, he or she is destroying your life.’ And then once you’re out of it, you see, ‘I was so miserable.’ But I wouldn’t say I was miserable doing Pennywise because I had a lot of fun with it as well.”

Portraying a monster is difficult to begin with, but at least with a human character who does monstrous things, there is a glimmer of a soul amid the emptiness. But Pennywise is just another mask for the nameless, shapeless evil known as “it,” which has a manic, bloodthirsty glee.

Brooke Palmer/Warner Bros.; Inset: Randy Holmes via Getty Images

“After we wrapped, I was in my childhood home in Sweden, sitting having coffee with my mom at our kitchen table, and realized, ‘Oh, holy sh—, I don’t have to deal with this relationship anymore!’ It was a very quick shift of just feeling

, like, ‘Oh my God, I’m relieved that I don’t have to deal with the darkness of the character.’ I likened it to an exorcism – him exiting my body and getting rid of the Pennywise toxins.”

But after letting the clown into his head, Skarsgård found it hard to push him out.

“I was home, done with the movie, and I started having very strange and vivid Pennywise dreams. Every night, he came and visited.”

Appropriately, Pennywise took on different forms in these visions.

“It was in the shape of either me dealing with him, sort of Pennywise as a separate entity of me, and then also me

Pennywise in circumstances that I didn’t appreciate,” Skarsgård said. “Like, I’m Pennywise and I’m really upset that I’m out in public and people are looking at me.”

The actor is aware there is an evil interpretation to these dreams (Stephen King wrote a whole book,

, about a fictional creation that comes to life independently to terrorize its creator), but Skarsgård thinks it was just his psyche’s way of gradually de-Pennywise-ing itself.

“This was a process of letting go of the monster,” he says. “It was amazing. It’s a daunting but exciting thing to sort of revisit him again.”

Of course, Pennywise will be back in the planned 2019 sequel,

, which will focus on the other half of King’s novel, when The Losers return to the town of Derry for a final confrontation with the creature they thought they defeated long ago.

Skarsgård and the killer clown are separated, but they’re staying in touch in the dreamscape.

“I’m good with it,” the actor says.