re: Why is the Grandfather-grandson relationship so special?

Easy answer. Two parts. One, grandparents don’t live with the kids full time typically thus proving Sextus’ adage absence make the heart grow fonder.

Two, most grandparents are either retired, or nearly retired, and aren’t having to stress about getting ahead, meeting deadlines, etc. professionally. They appreciate the time they have with the grandkids more making it all around a pleasurable experience.