The bestiary says they "gain a key class level," when they level up. Does this mean they take their first level or appropriate cohort level in say, fighter?
So, in example;
If I'm level 10, then my max cohort class level is 8 according to the CRB.
If I get a monster cohort and then we both level up (so I go to 11 bringing my max cohort level up to 9), will my monster cohort have the level up bonuses of a level 1 fighter or a level 9 fighter?