Space Mowgli

A human boy survives a spaceship crash and grows up alone on an alien world, shaped by an unseen and unknowable intelligence that raised him after his parents died. When a Terran crew finally locates him years later, they face an impossible question: whether pulling him back into human society would save him or destroy what he's become. A quieter, more melancholy entry in the Strugatskys' Noon Universe.