WP Biographia should, I think, be able to support what you want to do ..
Firstly, ensure all your users have a full biography in their profile under About Yourself, Biographical Info and a short or excerpt biography, also in their profile under Biography Options, Biographical Excerpt.
Then from the Dashboard, navigate to Settings, then WP Biographia and click on the Display tab.
Ensure Display On Individual Posts is checked and Display the excerpt of the user's biography is selected.
Next, ensure that Display On All Post Archives is not checked, Display On Author Archives is checked and Display the full text of the user's biography is selected.
If I'm reading your original post correctly, this should give you what you need.