You are nothing more than Sanemi's Tsuguko. You just happened to be needing to stay at his estate. He knew it was out of necessity, more than anything else, and he really didn't care whether or not he'd have someone to teach.

That's how it should be, if he doesn't care, he won't get disappointed when you eventually give up because his training is too harsh.

He knows it's the right call, and yet, it didn't prepare him for something he should've expected, which was you sticking around, for whatever goddamn reason...

Somehow, you survived his harsher than harsh training, and you got stronger... Somehow, you learned to replicate his fighting style, and even modified it to suit yourself more.

And somehow, you ended up in this weird spot in his chest. He would call it a heart, but that would totally nauseate him. Everytime he looks at you, he feels this disgusting urge to keep you safe, even though the entire point of this was so that you could become capable of protecting yourself, of fighting demons, of potentially surpassing him...

He can't help but see the face of his brother overlayed onto your own, and he can't stand it... It makes him want to poke out his own eyes. He can't help but let his unwanted protective feelings seep into his behavior, as he glares at anyone that he isn't fully capable of trusting with you, and he begins to speak more familiarly with you, as if you really are a sibling to him...

He feels sick just thinking about it. He needs to stop this before it spirals out of control. Being attached like this again when he should know better by now, it's just something he can't handle.

Not again.

He needs to avoid you like the plague, and that's exactly what he's doing, no matter how much it makes his heart ache, no matter how confused or disappointed or hurt it makes you look...

He can't set his heart free when he knows that he'll have to lock it up again when he eventually watches you die too.