The Drode is evil, and is often sent on missions for his master Crayak, whose proclaimed goal is to eradicate all life in the galaxy and remake it in his image. The Drode appears to the Animorphs several times, playing mind games with them, and seems to hold a special "fondness" for Rachel due to her viciousness and drive (similar to Crayak's particular obsession with Jake, out of revenge for what Jake did to his Howler shock troops). He and the Ellimist often appear opposite each other, with the Drode a snippy and angry foil to the usually serene and wise Ellimist. Interestingly there seems to be no good equivalent to the Drode on the Ellimist's side, though the Ellimist, with his almost unlimited power, probably doesn't need one. (For that matter, there is no known reason why Crayak would need a servant either; presumably Crayak simply would rather send a messenger than directly show himself, as the Ellimist does.)
Though very powerful, the Drode has certain restrictions on what he is allowed to do, defined by the rules of Crayak and the Ellimist's "game." In The Exposed, for example, he says he is not allowed to destroy a sentient life form, including intelligent animals such as whales (it is unknown if he means for that particular mission or at all). However, he is able to find loopholes to these cosmic laws, such as destroying the Chee (sentient androids don't count as "life forms"). Within this book he acts (as Rachel describes him) like a puppetmaster, manipulating the characters to do his will through a series of thinly-veiled supernatural occurrences.
The Drode is similar to the trickster character in many legends, in that he has great powers and often uses them to amuse himself; however, unlike many tricksters, he is also truly evil, and at times wistfully expresses a desire for bloodshed and viciousness. Nevertheless the Drode seems to enjoy his trickster personality, and acts almost like a cartoon character at times---for example, pulling a giant watch out for comic effect, while giving the Animorphs a few minutes to decide the fate of the world.