If kept on a craftworld O can see it being as miserable as Commoragh in irs own way. A sterile world that can observe every thought among the few survivors who was brought onboard with you. With psionic implants embdedded inside you analysing your thoughts and put you to work on a chosen path.

While there is no sadistic cruelty in the tasks given to you. It feels like it was designed just to whittle away your mind to keep you perfectly docile. A psyker may be tasked aiding the bonesingers in their wraithbone works and subtly debased for your inferior bonesigning akills. Others take the path of artisan and servant as eternal apprentices. Never mastering the trade asked of them. Their finest work making an amateur artisan look like a rejected work. Humans given the task of handling the more malignant dreams an Eldar may feel knowing failure will have the horrors coursing their mind and leaving them unable to do anything but scream in complete dementia for all eternity.

Such is the depressimg life as a Craftworld prisoner.