Eugene ' s World Eugene ' s World was a pocket universe created as a prison for Eugene Tacitus as punishment for the murder of his son . Society . The world took the form of a medieval castle , and the technological development remained mostly consistent with this impression : the prime weapons were sword s , but firearm s were occasionally used — most often for ceremonial purposes . The people were ruled over by an emperor , who was proclaimed a god and would rule over his subjects as a ( mostly benevolent ) despot alongside his wife . All aspects of society were dominated by the ruling monarch , and in turn , his subjects accepted his decrees without complaint , only showing signs of discontent if an emperor ever admitted to not being a god — which would result in his summary execution . In keeping with his status as a god , the emperor was followed by a royal scribe tasked with recording all events of the sovereign deity ' s life , no matter how banal , and entering them into a Holy Bible ; however , few people would ever read the bibles except for the scribe , for they would only be completed upon the emperor ' s death — whereupon he would be declared a false god and the bible promptly became invalid . In reality , the castle was purely a constructed world . Nothing existed outside the castle — indeed , the people had no concept of " outside " . Eugene Tacitus , the Emperor ' s Scribe , was the only real person in the realm and the only inhabitant with any influence other than the Child : all other characters were merely mental constructs created by Tacitus , their lives dictated by his imagination . However , after centuries of imprisonment , Tacitus had forgotten who he really was — apparently out of a conscious effort on his part ; he would only become aware of his true identity and power over the fiction at the end of every Greater Cycle . ( AUDIO : " The Holy Terror " ) History . The Lesser Cycle . Traditions , rituals , and events followed a very specific loop in this world . Upon the death of an emperor , he would be proclaimed a false god ( as evidenced by dying ) and his surviving wife would likewise be denounced as a false goddess and sentenced to death by torture ; throughout the castle , holy depictions of the former emperor would be destroyed en mass , and any citizens who still revered him would be executed for heresy . However , the people ' s loyalties and worship were easily transferred to the new emperor with only minimal casualties . Despite the previous emperor being denounced as a false deity , his neurotic son would nonetheless assume his role as imperial ruler . Meanwhile , the new emperor ' s deformed half - brother , aided by the High Priest , would lead a rebellion against the new regime ; however , the coup would fail and both conspirators would be executed . Unchallenged from then on , the new Imperial Couple would slowly become almost identical to their predecessors , particularly in their loveless marriage and growing sadistic tendencies : of the two sons they would raise , one of them would be born disfigured and turn out to be of illegitimate parentage , while the other would turn out soft - hearted and fearful — often suffering abuse from both parents for serving as a reminder of the father ' s earlier neurosis . Eventually , the emperor ' s reign would come to an end with his death , whereupon the cycle would repeat once more . ( AUDIO : " The Holy Terror " ) The Greater Cycle . After countless cycles of Royal Succession , a different and larger cycle would unfold as a recurring punishment for Tacitus : his son would be reincarnated as one of the characters within the universe , easily recognised by his face regardless of the character he ' d appeared as . Possessed of seemingly limitless power , he would kill everyone in the castle in a homicidal search for his father , ultimately destroying the entire world in the process and rendering it down into formless void . Forced to see the fantasy he had taken refuge in destroyed , Tacitus would remember who he really was and what he had done , and the Scribe would be forced to kill his son once again ; Tacitus would then re - build the world and begin the cycle anew , immersing himself in the fiction until he once again forgot who he was . Into the end of one such cycle stepped the Sixth Doctor and Frobisher . The world was structurally similar to the extra - dimensional space created inside a TARDIS , and it was this that drew the Doctor ' s TARDIS to it , the TARDIS requiring a similar environment to itself to recuperate after Frobisher interfered with the dimensional stabilisers . In this particular cycle , Tacitus ' son was incarnated as the son of Childeric , the current emperor ' s half - brother : the centerpiece of a delusional scheme to create a true god , the child had been raised in complete silence so that he would not be " contaminated " by mortal language , Childeric going so far as to cut out the tongues of anyone assigned to care for the child — including his own wife , and later his servant Arnulf . The child willingly played his role as a young god up until he realised that Childeric wasn ' t his " real " father , whereupon he tore Childeric apart and began his search for Tacitus . Meanwhile , the new ( and final ) emperor abdicated his throne to Frobisher , who attempted to break the cycle and give free will back to the people . Unfortunately , the people were massacred before Frobisher could get them to understand the concept . The Doctor also attempted to get Tacitus to break the larger cycle by convincing him not to kill his child , offering to help him escape from the prison once and for all . However , though Tacitus successfully resisted the urge to continue the cycle , he could not forgive himself for what he ' d done and had his son kill him instead . With no further reason to exist , the child and the remains of the pocket universe dissolved into nothingness , leaving the Doctor and Frobisher to solemnly depart . ( AUDIO : " The Holy Terror " )