Have watched so many police dramas so here goes ;
the lead cop always has a troubled home life ,usually a bad marriage split
if they have kids they always have a poor relationship with them as they have prioritised their job
if there are male and female cops partnered there is usually unresolved sexual tension
the older cop , usually gets paired up with a younger colleague who they dislike - there is usually always a back story e.g previous partner got killed
there is always one cop who doesn’t follow rules. Doesn’t wait for back up and gets caught with the baddie / put in danger
the lead cop always is a workaholic , takes evidence home - never any issue with that
they go and speak to a retired cop who remembers every detail about the case from decades back
They usually have to chase a suspect , bonus points if there is a metal fence that they have to climb over