Feelings were a mystery to Aigis, but friendship and love in particular were, thankfully, revealed eventually in the form of Minato, opening her up to a whole new level of observation she had never reached before. When she finally noticed what it was that she wanted from Minato, what it was she felt and yearned for, she searched her past for clues of this feeling in others.
It was easy to see in Junpei during his time knowing Chidori. Yukari seemed to feel similar things for the entirety of SEES, while Mitsuru felt the same in a much more subdued fashion. Fuuka and Minato were tougher, seemingly closed in on themselves in many ways. Minato especially scared her, since he showed no sign of caring for anybody, at least within SEES. She vowed to collect more data on his treatment of his other classmates in the future.
Akihiko and Shinjiro showed up many times in her databanks, almost always together for the entire month that Shinjiro had joined them. There was never a moment to pinpoint, but observing the two of them and feeling a faint tugging sensation in the center of her chest, Aigis was aware that she wished she and Minato could look like the two of them.
While they were closed off to nearly every other SEES member, Shinjiro and Akihiko were nothing but open to each other.
And that was how Aigis knew.
A/N: I feel like I took a lot of liberties with Aigis' character on this, so I apologize if she seems really ooc. I really love Aigis, but she was such a hard character for me to nail down for some reason, and I almost completely rebooted this chapter to something not even close to what it is to try to fix that, but just never actually did so.