What are you, some kinda science bitch?
Joking aside, that is some astute reasoning and observation. It makes sense. But I feel like there is a distinct chance that the devs didn't really consider all that and just made some cool looking monsters. Still, everything you write about the insect like hive structure and what we've seen so far checks out.
Markus makes it a point in most cases to defer to the MC in their quest for a mate, even before the parasite. He is a wingman for MC x Adara. He gives first dibs on Kiara to the MC and goes off to find his own random blonde in the camp. He never made a pass on MC's mom or sis I think.
However, there are some clues that deviate from this. MC and Markus are both smitten by Celeste and jokingly argue about who got dibs on her lol. I doubt this is cause for real friction between the 2, but it certainly wouldn't be surprising if sharing and tag teaming bitches is on the horizon (optional, most likely). If I wanna force some symbolism, I might even refer to her hair color curiously being split into the 2 parasites' colors. "I take the black side, you take white bro!"
Also, there is one big trope that leads me to believe that friend turning into enemy actually has a pretty high chance of happening.
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A scene like this early in the story is often foreshadowing for friction in the relationship. A lot of times, it does get resolved in a bittersweet way like the ex-friend saving the MC at a pivotal moment, but I think it does signify an arc where they turn on each other, not because of hate, but because their convictions are at odds with each other.