An interesting interpretation of the Nameless Boy's last request, even though he had no way of knowing about Fushi's immortality, being remembered was considered a sign of immortality in older cultures. By having an immortal being remember him, he lives on forever.
See The Last Unicorn's quote “As for you and your heart and the things you said and didn't say, she will remember them all when men are fairy tales in books written by rabbits.”
Given that manga covers have the boy's purple eyes seems to give credence to this idea.
Why does the Beholder insist on Fushi experience the deaths of those he loves? What greater stimulus outside of love and pain is there for people to feel? The death of those you've come to love and care for.
There weren't any humans within potentially hundreds miles of the Nameless Boy's Settlement given how long it takes to get to the village in episode 2. Did anyone in the settlement ever have a chance to survive?
Did the Beholder know to put Fushi there because he'd run into the boy?
What would have happened if fushi ran into a sociopath, psychopath, etc. first instead of the kindhearted Nameless Boy?
The Beholder tells Fushi to collect everything around the world and only then would he give the immortal "freedom". He even notes that when Fushi was living "normally" with Gugu and the others, he received little stimuli which meant he couldn't create as many things. It's only when he either actively seeks things out, or tries to hide from his problems does he get more stimuli, which means more memories that last in the things he creates. So when Fushi creates a husk of the recently deceased princess and it turns out he can bring back the dead if he does it soon after they die, the only reason the Beholder hasn't told him is because the deaths that Fushi experiences brings the most stimuli to Fushi, meaning he can recreate the objects or beings easier. His suffering leads to his s strength increasing.
