Violas are supposed to be warm, friendly and docile. This one isn't. There are noises like bowing the body, screeching unclean harmonics, very bright sul ponticello... And also phat sustains and sul tasto sustain and staccato, to balance things out.
Layering multiple articulations and creating emulated small sections by using unison mode are included, of course.
Demo by Aku P, also using Vengeful Bass and the synthesizer instrument from Vengeful Cello:
And a darker demo by Mateusz Moś, also using the bass and cello: