Anima Ex Machina: Extra #2 [Pronouns]
Keen readers might have noticed a little quirk in every scene involving Adam: the parasite is always referred to as "it" if not by name. This isn't an error.
To begin with, technically, the ixodida parasite is a hermaphrodite. It has functional male and female sex organs and can reproduce by itself. (The genetic code is simply recombined in cases where it self-pollinates, although the ideal situation is that the parasite fertilizes the eggs of another member of a sea -- in other words, another member of its species group. Parasites do not mate for life. Parasite-hosts do, but this is a tangent for another time.)
However, when it fuses to a host (such as a human), it loses its own gender, and the ixodida as a whole is referred to by the host's. So, when you see a reference to a female ixodida, it actually means that the host was originally female and that this carried over to the host-parasite combination.
Bill and Adam are a unique case. Whereas normally, an ixodida and its host are considered to be one complete being, the two main characters consider themselves to be mentally separate individuals. Hence, there needs to be a pronoun for both halves. Bill is obviously male, but because Adam lacks any functioning sexual organs of its own (until it decides to separate from Bill again), it's referred to as a completely genderless entity, not as a male or a hermaphrodite, because it no longer has reproductive organs of its own.
Yes, despite the fact that Adam looks like a male, inhabits a male body, and is technically hermaphroditic on its own, the correct pronoun to describe Adam would actually be "it," not "he" or "ze." No reproductive organs = no sex.
To make matters even firmer, Adam doesn't actually identify itself with a gender, either. This isn't a unique case. Ixodida parasites simply don't think about their sexuality or gender on a personal level. If they lack a host, then they view sex as a necessary process for survival, and because they're hermaphrodites with no inclinations for mating for life, this just means they'll mate with anything else that calls itself an ixodida. There's no actual passion or pleasure in it -- just survival instinct. When coupled with a host, the ixodida, as stated before, assumes the physical gender identity of the host and attempts to maneuver the body into playing by the host species' rules in terms of sex. (For example, a parasite within a male and one within a female will attempt to mate with each other in order to produce offspring.) Again, there's no real passion or personal sexuality involved because at this point, the ixodida is acting through the host out of survival instinct. As in, the ixodida itself, while conscious of its own individuality, considers the parasite part of its body to be nothing more than an extension of its overall form -- akin to the heart or brain. It simply adopts the host's gender identity because it inherits the host's body.
However, because Adam did not claim its host's body for itself, it creates a kind of paradox. On the one hand, it views itself as a separate entity from Bill, one that doesn't actually share his sexuality or gender. On the other, it still views itself in the same manner as most other ixodida view their own parasites: as an extension of the body but not a full creature on its own. So, it literally has no gender -- and not in the same way that a person might be genderqueer. Thus, Adam, in its own opinion can't be defined by any other genderless pronoun except ones that would also apply to any other body part.
That and it just makes Adam seem more alien, so... yeah.