Whilst I agree that Trish is usually at the heart of every argument, to me it's obvious that it's because she'll say something when she doesn't agree, or when there's something happening that shouldn't be. The reason no one else speaks up is because they'd rather slink off to their respective group and talk about it there!
I really liked how Trish handled it yesterday when Dylan was "apologising". He was saying how he knows Trish can take a row and likes a good shout. She immediately said, no I don't, I just raise my voice when someone starts on me. Dylan trying to paint HER as the instigator pissed me off!