I really like In Guilty Gear that there's never a moment where Ky confronts Sol when he learns Sol is a gear. Some other franchises might've taken the opportunity for some drama filled moment involving the two of them where the truth comes to light, but Guilty Gear doesn't, and instead shows their development through actions. It's not expressly stated when Ky learned Sol was secretly a gear, but he definitely knows by Overture. During Xrd their relationship has evolved more and the writers know that a scene between the two isn't needed because Ky has matured and moved past that part of his life when he'd feel betrayed by Sol hiding something like that from him. He has a better understanding of Sol and knows why he would hide his true identity. I do think part of Sol would've also expected Ky to confront him about it, but the conversation never comes. It's a mutual understanding without any words spoken that it's part of the past now.
