The relationship between a criminal and detective.
They have a personal relationship when the criminal does everything to avoid being discovered by the detective and the detective does everything to discover the criminal. The detective have to see different points of view to find conclusions at the cases and always think about everything with the word "and if?*
The criminal have to plan and investigate all the circumstances in which place or situation he could be discovered, he uses different clothes to be unrecognized or gloves to hide his fingerprints.