Despite being a two-headed dragon, both Zak & Wheezie are complete opposites of each other:
- Zak is neat, quiet, orderly, stubborn, arrogant, & pessimistic
- Wheezie is wild, loud, friendly, free-spirited, crazy, & optimistic despite her tomboyish beauty.
They're real music lovers, and skilled musicians; they make up a "one-dragon band" which can even play scales on their scales. At times, their opposite personalities can lead to disagreement, but harmony returns when they learn to respect and listen to each other. They'll try anything to get away from each other in moments of anger and despair -- in one episode, they found a magical chant that separated them, or the "alone cone", which isolates one head from the other--but in the end they're always glad to be reunited.
In the episode, Giant of Nod Wheezie mentions that she is older than Zak, however Zak and Wheezie are twins. Their musical-note badges light up when they can find a way to meet a difficult challenge–like getting along with each other. As with most brothers and sisters, they don't agree on a lot, but when they put their heads together, it's music to their ears.
- In real life, if two people shared portions of a body as Zak and Wheezie do, they would be called conjoined twins, but all conjoined twins are the same gender.
- Zak and Wheezie may be the oldest of the gang, maybe 7-9 years old.
- Zak's catchphrase is "Take it easy, Wheezie!" while Wheezie's catchphrase is, "Loooooooove it!"
- In the Episode "Try It, You'll Like It" Zak & Wheezie's Stomach Growled