Okay brainlet, for you in the back one last time.
They're all called Parasites and the connection they make is initially a neurological and emotional one that triggers a biological connection. I'll copy paste some notes on types of symbiosis here
"Symbiosis: Mutualism, Commensalism And Parasitism
The species in an ecosystem will interact in different ways. These interactions may have positive, neutral or negative impacts on the species involved.
The term symbiosis can be used to broadly refer to these types of relationships as it directly translates to mean living together (sym: with; bio: life).
Symbiosis is the ecological relationship between two or more organisms living closely together with some form of feeding relationship involved. The three main symbiotic relationships are:
- Mutualism, where both organisms benefit.
- Commensalism, where one organism benefits while the other organism is not harmed.
- Parasitism, where one organism benefits and causes harm to the other organism."
So the relationship changed from one sided Parasitism to Mutualism, and since the trigger for the whole relationship is a neurological connection via technology, mind over matter makes sense.
Or to put it in different words. All parasites can only exist in symbiotic relationships by feeding from a host. Consuming was mentioned a number of times in previous episodes, and Zero Two consumed her previous partners (and almost consumed Mitsuru). Compatible partners have a relationship based on Mutualism where they feed off each other. Hiro was always capable of that with her, but that capability was dormant and not awakened until that moment (Hiro's dormant ability and awakening it was also mentioned by Zero Two in episode 1)