Alright, I'm going to try to explain how I "play" Nirvash . . . This will get confusing like the rest of E7.
✘ Nirvash is alive!
Not only is it alive, it is an organic life form to boot! It has its own thoughts, behaviors, and so on. However, it lacks an ability to communicate with organisms other than Coralians, and it cannot move on its own at all times. So, Nirvash is, in essence, a vegetable. It is aware of what is going on around it, but it doesn't have the means to interact with the environment.
However, these facts doesn't always hold true. At times, Nirvash will move without a pilot as a result of its own will, proving that it is aware especially considering how and when it moves. Also, Nirvash is able to speak with Renton and Eureka in spoken language at the very end of the series, showing an ability to speak. Within camp, the former is only viable option, though.
✘ But it's a big fighting robot . . .
That it is! Nirvash was not created to become a weapon, though. The organism that created Eureka and Nirvash, Scab Coral, had intended for Nirvash to serve as a companion for Eureka when she went out into the world. When Eureka and Nirvash were found by humans, it was the scientists that figured out that Nirvash could be used as a robot. That is, unlike Eureka, Nirvash couldn't move under its own power. However, once electrical pulses were applied to certain locations, it was able to! With some guesswork and plating, Nirvash came to be retrofitted as the first mecha in the Eureka Seven world.
✘ So, it has a personality and so on?
Mmhm. Nirvash is a character in its own right with its own drives and ambitions. First of all, unlike Eureka, Nirvash has a greater awareness of the world around it. Scab Coral created Eureka to serve as an emissary to humanity, while it created Nirvash to serve as her guardian. For that reason, Nirvash is given a larger understanding of its existence as a Coralian, including Eureka's, as well as having a mission to uphold while Eureka is given no information of any kind. As for its mission, Nirvash must deliver Eureka and her human partner back to the core of the Scab Coral.
This task is more complicated than it appears, however. Nirvash does not state its purpose nor Eureka's purpose in appearing to humanity; this is driven largely by Holland a la Norb, Doctor Bear, and other human characters. Instead, it remains largely silent, which is not surprising considering its medium. Nirvash can only speak to Eureka who spends a great majority of the series learning to interact with humans and come to terms with herself as was Scab Coral's intention. To keep from interacting with humanity because she is more comfortable with a Coralian was not that Scab Coral's intention, but it also knows that a Coralian alone amongst humanity quickly loses its way. So, Nirvash must preserve a balance within Eureka. In this way, Nirvash serves as the knowing albeit frustrating guardian to an inexperienced ward.
So, where does a personality emerge? Well, it's difficult to construct one that isn't mediated by Eureka. She is inept in a number of areas, so what would be understandable to someone else is confusing for her, especially when Nirvash wasn't created with a stripped awareness like she was. Still, Nirvash is able to make itself known in a number of ways, though usually only in grand gestures. So, in that spirit, Nirvash will often refuse to fly, or will fly without Eureka, move of its own accord, and even rebuke Eureka with physical injury. At these times, Nirvash is able to put in its two cents on a matter without having to communicate through Eureka.
As an example, in the beginning of the series, Nirvash refuses to fly for Eureka, forcing the Gekko State to visit Garage Thurston for a device that they hope will solve the problem. While they do acquire the device, something that allows humans to interact with Nirvash, they also convince Renton to join them in their resistance. Now, Renton's recruitment is originally Holland's and Eureka's idea as a means of making the Nirvash functional; they have other plans in mind. However, Nirvash is satisfied with this outcome. It refuses to fly for Eureka, because it is frustrated by her failure to try to find a partner, already recognizing that Holland is not it. In collecting a device that allows for a human pilot, one step towards acquiring a partner is met. Then, soon after, that very partner is found! Before anyone else realizes it, Nirvash already sets its hopes on Renton being Eureka's partner. So, often without having means to make itself understood, Nirvash can effect the direction of events.
. . . . . . . . Then, I could not make myself finish off the rest of this. Note to self: Nirvash in Camp, Nirvash and Eureka, and Evolution of Nirvash.
QUESTIONS, CLASS?