BIONICLE started off featuring easily-angered Toa of Fire Tahu and Not Good with PeopleToa of Ice Kopaka. However, later teams would invert this; Jaller was a Toa of Fire yet calm and professional as The Captain, while his team's Toa of Ice, Matoro, was quiet but compassionate, determined, and The Chosen One. The Bara Magna setting has another inversion, as the fire tribe warrior Ackar is old and thoughtful, while his best friend, Kiina (with the water tribe), is a brash, sharp-tongued Ladette.
Inhumanoids brought us the duo of Pyre (Fire spirit) and Crygen (Grey ice spirit), both of which can fuse together into the guardian of the Earth's core, Magnacore!
As with the Earth Corps humans, Herc Armstrong is the fearless Red oni while Liquidator is the more calm and collected Blue oni. Although their file photo shirts are the otherway around, Herc's green exploration suit has more red on it than blue...while Liquidator's yellow suit has it the other way around.
Of course, if you want Herc as the blue oni, contrast him with bad boy Auger's red oni. And Liquidator can only be red oni to the blue oni of Dr. Derek Bright (who himself wears the blue exploration suit).