SPOILER ALERT: Do not read if you have not yet watched “Brand New Cherry Flavor,” streaming now on Netflix.

Netflix’s new limited series “Brand New Cherry Flavor” promised twists, turns and kittens right from the start, but it’s hard to imagine anyone could have guessed exactly how those felines would come into play.

It seemed innocuous enough at first, with a mysterious woman going by the name of Boro (Catherine Keener) cradling a cat at a Hollywood event. There are enough eccentrics in Tinseltown that characters barely batted an eye. But after budding filmmaker Lisa (Rosa Salazar) took Boro up on her offer to put a curse on a producer (Eric Lange) who misled her and put her in a #MeToo situation, it was revealed those cats were Boro’s payments. And they were coming from inside those with whom she struck deals.

Usually, Lisa vomited up these kittens, but after asking Boro to make that stop, she ended up birthing one from a new orifice that tore itself in her torso. (Needless to say, the discomfort of that proved to be a one-time thing, and Lisa went back to accepting the oral alternative.) The written description came from the minds of showrunners Nick Antosca and Lenore Zion, but the look of the newborn kittens were a collaboration between an on-set puppeteer team and the visual effects team, lead by VFX supervisor Danny Yoon.

“I think where special effects is really effective when you do start with a base in something physical and real,” Yoon tells Variety, noting that a lot of what he loves about his job is “helping people tell the stories in either creative or invisible ways.”

This came into play in the kitten scenes in a number of ways. First and foremost, Yoon reveals, was removing the puppeteering rig from every frame of footage from these kitten sequences.

“The kittens have these puppeteering rods that have these wires that go in that manipulate the little features in their faces,” he explains. “It’s pretty painstaking, tedious work. You have to isolate the kitten, so you have to rotoscope it out — you’re literally cutting it out on the frame. And then once you have it isolated, then to remove the rigs, you have to recreate the frame behind the rigs and you have to track that all in. So, those are the invisible effects that we do.”

From there, he and his team had to ramp up the emotion on the kittens’ faces and make sure they looked like they had just come out of Lisa’s body. Although Salazar really did spit something out of her mouth on set, visual effects was responsible for increasing the size of what was coming out of her in those moments so “it filled the mouth,” Yoon points out. They also had to add “bloody, pinkish slime” to the kittens’ coloring.

“Nick and Lenore especially wanted that expressiveness of this fragile kitten. At points in the rough you could tell it’s a puppet — it’s a little stiff — so we had to put in every little blink, mewing at certain points, we had to make it more slimy and shiny,” he says. “We just put procedural effects that add additional lighting to it. It’s pretty standard stuff that we use as a toolkit. But for the eyes and the mouth, we [use] 2-and-a-half D effects, so we track in a matte painting of the mouth and then we literally animate the stills.”

“Brand New Cherry Flavor” filmed amid the COVID-19 pandemic in the summer of 2020, which meant visual effects were all done remotely, to adhere to new safety protocols. Yoon had previously worked with Antosca on his Syfy “Channel Zero” series, which helped him immediately understand what the producer would be looking for on this series. Despite new working conditions, “‘Brand New Cherry Flavor’ was peanuts compared to ‘Channel Zero,'” Yoon says. “That really prepped us for the demands of this show.”

Establishing the look of the initial kitten sequence took his team about five days, but once they got the hero shot down, he says they were able to speed things up for the rest of the times the script called for Lisa to cough up a cat.

After the first time the audience sees Lisa go through such an experience, they may be waiting for it to happen again. So Yoon wanted to ensure each new time it did, it came with an elevated gross-out factor. Most commonly, this required “spit addition.”

“You can’t have enough slime, so we have to make it look wet. We call it re-lighting: you’re using the image itself to add highlights, and then we did have to put more spit coming out of her mouth,” he says.

When it came to the birthing scene, which was graphic by the nature of her skin splitting open, practical effects once again proved vital.

“The second orifice was the whole side of her torso and [the special effects team] just pushed it out,” Yoon says of that kitten expulsion. “We had to isolate the orifice and make it look wetter and bloodier. And of course they had this blinking light in the scene, so we had to painstakingly color correction and animate the skin. The rig itself was just lit normally and it was static, so we had to track it in with the way her natural torso works and just make it look seamless.”

Perhaps surprisingly, Yoon says the kitten scenes were relatively easy to create on his end. More challenging for him was both the jaguar demon and the scene of Mary (Siena Werber) plucking out her own eye and eating it.

The former was complicated because it was one example where the production plates the visual effects team received were simply not scary enough and required Yoon to do a lot more research. “They had this dancer in this rubber suit and you can feel it’s a rubber suit. So, we didn’t really know from the script or production what we really needed to do with it,” he says. “The idea was that this creature was in between dimensions. We had to make a clean plate because otherwise you’d see a double image because we were stacking it on top. Then we blurred it, and that was a really complicated process, then we added the glowing eyes. That was quite a transformation from what was shot.”

The latter was a scene within a scene: Mary’s drug-induced actions are captured for Lisa’s short film, which the character then watches to understand what happened to her. Since she has to reach up and pull her eye out of her face, production shot one plate of Werber “reaching up to a prosthetic face to really dig into that eyeball,” Yoon says. “Then during the transition of her going down to eat it, that’s a plate of her eating.” His team not only had to merge the two plates, but also create the blood effect.

“There’s only so much practical fake blood on her, and they really want it to be streaming [down her face], so then you have to track it, and tracking on a face that’s chewing, that took a while,” he admits.