I can't say i understand your feeling but i think knew your feeling to Kyousuke :3, well actually from my point of view, his life is that exact moment, the interactions with his sister and his sister's friend, well that's it, and he has his existence, life, and achievement, how come you overlook that, that point when he struggle to keep his sister safe and happy, and his sisters's friend though.
His sister is nothing without him, well Kirino is pretty much a strong girl, but without Kyousuke, she might be broken down already, Kyousuke is strong, loved by many, and he does have a hobby, watching some indecent stuff :3
ups i think you need to put "spoiler alert" in the thread title.