Hi

Passionate at her best, and emotionally volatile at worst, Lisa never does anything halfway, and that includes how deeply she feels each and every emotion.

I think I understand the meaning of "at her best" and "at worst", but I'm still not quite sure what the author wanted to say in that bolded part of the sentence?

EDIT: Or maybe it means in the best case she was impulsive and in the worst case she was emotionally unstable?
Senior Member4,464
You could read best and worst as "on a good day" and "on a bad day", or "when she's in a good mood/bad mood".

Does that help?
Senior Member2,170
Proficient Speaker: Users in this role are known to maintain an excellent grasp of the English language. You can only be promoted to this role by the Englishforums team.Trusted Users: Trusted users are allowed to use additional capabilities of the site such as private messaging to all users and various other advanced features. You cannot join this role unless you are promoted by an administrator.
Live chat
Registered users can join here