I can relate to this chapter pretty hard, as someone with a large-ish age gap from my younger brother I'm almost like a third parent/uncle at times. We grew distant while I was away for college and when I moved back in town, we had a rare chance to reconnect without our parents in the background. It changed our relationship completely (for the better), and seeing this go a similar route is really cool to see.
@Tcof that's encouraging to hear! No NTR is the right amount of NTR. There really aren't enough natural sibling relationships in manga so I was hoping that this author wouldn't screw it up.