Which is it for you?
For me it’s that episode from Final Singularity (see a screenshot in the post). After seven singularities he meets us again, like older brother watching our struggle from the temple. And then he describes the singularities we went to, while he watched over us all that time and wanting us to overcome the obstacles. It’s incredible sad to realise he’s dead now and will not meet us again in the end of Lostbelt story to describe our journey through seven lostbelts and congratulate us with finishing our goal and saving the humanity. It’s just feels not fair that we will never see him again.