According to the Parasyte manga and the anime, the parasites had one primary objective: burrowing into the head of a human being, eating its brain, and then puppeteering its body to eat other humans. If the host died, the parasite died, too. However, the parasite that got into Shinichi Izumi and the one that was in Mamoru Uda didn’t get to the brain and hence turned their respective hosts into mutants. Due to their symbiotic relationship, the parasite learned how to be more humane, and the human became more desensitized to violence and death. Through Su-in and Heidi, Parasyte: The Grey evolved this aspect of the host-parasite dynamic with the help of a Doctor-Jekyll-Mister-Hyde-esque twist.
Spoiler Alert
How Did Su-in Turn Into A Mutant?
In Parasyte, Migi accidentally inhabited Shinichi’s hand because it couldn’t get into his head. Then, it had to adapt to that situation, become more learned, and find ways to make Shinichi agile during the violent altercations between humans and parasites. But Migi’s greatest test happened when a parasite pretending to be Shinichi’s mother pierced his host’s heart. Since Migi had spent a lot of time in Shinichi’s body and had an idea of human anatomy, he managed to keep him alive. In Parasyte: The Grey, Heidi didn’t have that advantage. When she accidentally entered Su-in’s body, she was already bleeding after being attacked by an incel. To ensure that her host didn’t die, she had to close her wounds and then establish some form of symbiosis with Su-in. And that led to an interesting conundrum that wasn’t seen in the manga, the anime, or the live-action movies.
What Were the Limits of Heidi’s Powers?
You see, in the manga and the anime, Migi needed around 4 hours of sleep every day to stay functional. During those moments, Shinichi would be vulnerable. When Migi’s powers began to mix with Shinichi’s physiology, that issue decreased. During one particular altercation, Migi morphed himself into a scythe-like weapon and then went to sleep so that Shinichi could defend himself without his support. Due to the circumstances under which Heidi became a part of Su-in’s system in Parasyte: The Grey, she could stay active for a mere 15 minutes at a stretch. So, Heidi had to use her powers very judiciously in order to protect Su-in. On top of that, whenever Heidi used her power, Su-in would become unconscious. When Su-in would regain consciousness, she’d have no memory of Heidi’s actions. It’s like Fight Club, but instead of Tyler Durden, it’s a parasite called Heidi. That said, Su-in retained Heidi’s ability to telepathically locate other parasites around her even when Heidi wasn’t in control of her body and mind.
How Did Heidi Communicate With Su-in?
Due to the aforementioned handicap of sorts, Heidi couldn’t constantly converse with Su-in. Heidi used Su-in’s notepad to communicate with her. She passed on information to Su-in through Kang-woo. And interestingly enough, Parasyte: The Grey brought back the subliminal space, which we saw in the manga and the anime (and was completely missing in the live-action movies), to allow Heidi and Su-in to talk to each other face-to-face or consciousness-to-consciousness. Even though it might seem that the lack of communication between the host and the parasite will be detrimental to character growth, the frugal use of this gimmick actually gave every interaction between Heidi and Su-in a sense of importance and gravitas. Also, the subliminal space created by Heidi had some brilliant VFX and CGI.
How Did Heidi Manifest Herself?
Talking about the superpowers, Migi could transform Shinichi’s right hand in various ways, form multiple versions of himself, and even detach himself from Shinichi’s body for brief periods of time to function as a separate entity. Based on what I have seen in Parasyte: The Grey, Heidi doesn’t have that much flexibility yet. She could extend her tentacles from Su-in’s face and perform extraordinary feats while she was in control of Su-in’s body. That didn’t seem like a lot, but as underscored by the parasites, since Heidi’s sense of self-preservation was very high, she became the strongest of the lot. I don’t know how Yeon Sang-ho intends to evolve the superpowers that Su-in has because of Heidi, but it’ll surely be interesting to see Heidi use a myriad of defensive and offensive tactics to support Su-in.
How Did Heidi Support Su-in?
While Migi had a lot of time to learn about Shinichi, Heidi had to take a crash course. But that didn’t stop her from empathizing with Su-in almost instantly. More than the action-heavy stuff in Parasyte: The Grey, I liked that Heidi quickly realized why Su-in felt so isolated and lonely. She never mocked her for that. She didn’t push her to do stupid things under the guise of being “more sociable.” Heidi let Su-in be herself while assuring her that she would always have a friend by her side in the circus that was unfolding because of the arrival of her species and the general stupidity of humankind. I mean, when Heidi told Su-in that she’d never be alone, I was on the verge of tears because I understood how much that must’ve meant to Su-in. On that note, here’s to more adventures with Heidi and Su-in.
