A lifetime
It was the only possible explanation. If Lyn were still that woman's pupil, he would have realized by now. Rhys did sense something similar about the two, the aura, and sometimes the way they spoke. But, that was not enough to make a link between the two of them. Besides, they use entirely different magic from one another.
Usually a master and pupil share similar magic, but that is not the case.
Sumire smiles. "It was more like a silent agreement and not an official contract. When I was young, I'd often try to sneak out the castle, and it was during one of those escapes I met Lady Penelope. She was working hard then to restore her clan than to its former glory and to surpass her seniors. I admired her for that."
So that's how it was, it was a coincidence that they met. Though it doesn't explain why they have the same scent.
Perhaps if he asks a bit more, then he will get his answers. When a person has high-level magic, a scent covers their entire body.