Complex sentence: He played a main character on "Victorious", portraying Andre Harris, which premiered on Nickelodeon on March 27,2010, also appearing as Andre in the crossover between "Victorious" and "iCarly", "iParty with Victorious".
Split into simpler sentences: He played a main character on "Victorious", portraying Andre Harris, which premiered on Nickelodeon on March 27,2010. Thomas also appearing as Andre Harris in the crossover episode between "Victorious" and "iCarly", "iParty with Victorious".