Hopefully you have an area for foxes and the rats because it would be a shame if niether had areas for themselves maybe some lore as to why you are in a prison in the first place?
There is lore reasons as to why Graphite starts in the prison, and a small opening cutscene is planned to be made at somepoint (probably just like an Undertale style slideshow with text). Short answer is that after the curse got apocalyptically severe, the king gave orders to just imprison anyone they suspected might be cursed, which included Graphite. They ended up surviving the longest partially because they were so deep into the facility.