Dan schneider (the director) had the idea that cat loved red velvet cupcakes, so they asked her to due it almost the exact color of red velvet cupcakes. Although, in a vlog
On the Slap, cat Said it was because her brother smashed a vase on her head and she like the blood red color her hair turned. But on all other occasion she say red velvet bolo de copo so...
there were already three brunettes on the show (tori, trina and jade) and since ariana is also a natrual brunette they wanted her to have a different hair colour!
