[ Subaru considers that in silence for a time. It seems he means to say nothing, until he abruptly disrupts that silence. ]

I spent two years trapped in...well. It's difficult to explain. But by the time I realized what was happening, it was too late to do anything but stop him from being drawn in with me. Then I could do nothing while he tried to protect the place I was confined.

[ Even though he's the older twin. Even though Kamui is impulsive and reckless and bound to get hurt. And now, here he is, unable to do anything for him again. ]

So in that regard, the last two years were not equal, if equality is the essential difference.