Kiel can be bratty and whining, when wanting food from Naofumi. Despite how she acts, she helps bring together the slaves, and acts as a sort of leader.
I thought she was growing to be a gluttonous battle maniac, but she was able to cook as well, showing a girly aspect.
Kiel has been shown to be a charismatic person by nature.
Her actions are shown to be too erratic.