Aria Isthill

Aria is a returning character from season 1.

The Ace of the New Erste Republic and pilot of the Astray Red Frame, Aria, along with Sebastian Ferrore, led the joint team that took down the Clavius Hive. It was humanity's first true counterattack against the BETA.

Her approach in life and in combat is simple: Focus on the task in front of you, ignore everything else, and crush it. Her preferred weapon both in a mech and in person is a sword. She's an experienced kendo practitioner.

From the beginning, Haru Yamada was fascinated with her. She wanted to be an Ace that could match up to the Crimson Blade.

Act 2
Shortly after arriving back in their Home World, Aegis encountered Aria and Sebastian. Their teams had been wiped out by a new type of BETA, so they boarded the Nuada and accompanied Aegis to Aries Colony.

After the disaster there, Aria helped defend the Nuada against the Space BETA, including the new humanoid type. Aegis felt they could trust her, and opened up to her about almost everything involving their strange circumstances.

She returned to Erste and promised to keep their secret.

Season 1
The would-be heroine of the story, many events came back to Aria. She was estranged from her husband, Kallor. She joined BML along with her daughter Key, and the two would go on to join the fledgling organization Blue Light.

Emmet Hyduk had altered Aria's memory on several occasions to block her knowledge of her own powers. She would eventually recover these memories and their associated power. She could telekinetically squeeze someone's brain, implant thoughts to influence them against their will, and eventually even effectively become invisible by passively erasing her existence from people around her. She could also visit a conceptual space in her mind, usually visualized as an infinitely expansive White Space. From there she could go into her own memories, or those of a partner she's extremely close to.

These abnormally strong powers go far beyond what a Newtype should be capable of, and are the result of the system of resets that form the basis of the multiverse. Countless times the world came to an end, and one person would be the architect of the next reality. In the previous world, it was Aria. The influence of being the world's creator gave her these stronger powers. Emmet, the only one aware of her role, sought to stymie her growth through the aforementioned memory manipulation.

Eventually she came to understand the infinitely repeating cycle was self-perpetuating, and as someone involved in it, there was no way for her to break free. In the creation of this current reality, she'd purposefully crafted it so new people untouched by the reincarnation system would be able to have influence for the first time. Those people were the pilots of Blue Light. Once she was fully aware of all this, Aria backed away from the group so as not to influence them, and let them forge their own paths.

This whole time Aria has been developing a closer and closer relationship with Sebastian Ferrore, to the point that they're inseparable. He decides to forsake the group as well, and the two embark on a reckless plan. They take advantage of a certain Angel's ability to travel between worlds, and Sebastian gets himself lost in there. Aria waits on this side and tries to psychically connect with him, then the two work together to create a hole between worlds. They enter it together and eventually come into contact with Akasha, the energy of creation behind the multiverse. Together they change the rules behind the multiverse so that in every world, at some point, Aria and Sebastian will come in contact with each other. It can be anything from a destined romance to a chance encounter to just meeting once in their lives.

In the epilogue, Aria and Sebastian invite Key, Elynra, and Anna over to their house. Aria is cradling her sleeping newborn. They explain everything that happened to their family, including making it very clear by abandoning the world and worrying about themselves, they have no right to consider themselves heroes like the rest of Blue Light.