It is kind of up to you.
My Lion Shaman treats her lion as her little sister, encouraging her to have a little fun and get into combat but to NOT endanger herself at all.
Her purpose was to make my playing the main character more enjoyable.
Lots of the time the Lion literally did nothing significant during the entire adventure.
Occassionally, when required (this was for PFS) she clawed some major ass when the group needed another damage dealer.