Fierceness
Ferocity
To state or express firmly
Assert
To disobey openly; to defy
Flout
Unwisely bold; rash
Foolhardy
Determined to have one’s way; stubborn and often recklessly willful
Headstrong
Clear and sharp in analysis or expression
Incisive
A) Frank and unreserved in speech; candid
B) Spoken in a frank, unreserved, or candid way
Outspoken
Not discouraged by danger or difficulty
Undaunted
Showing intense emotion or passion; forceful
Vehement
A) Pulsing with energy; vigorous
B) Having bright colors
Vibrant