The name actually is a misnomer, but only because they are more closely related to porpoises than to whales. They are definitely KILLER, no matter which was you slice it.
The ones who get caught and perform tricks for humans are either 'race traitors' or the sort of the mentally slow killer whales who can only learn to get their food by balancing balls on their nose instead of expertly hunting prey; and we should not judge all in the species due to the ridiculous trained antics of these 'Uncle Shamus', as other Killer Whales call them.
Highly-trained Killer Whales are known as Elites, and can snipe a seal from seventy yards.
They have been known to help dolphins like Ecco from time to time, but will not engage in either dolphin or human affairs of love and war. They have their own shit, man.