User blog comment:The Devil's Advocate WP/Weiss the Innocent Victim/@comment-10380701-20131104100843

This.

This is why I never showed any dislike for Weiss. We've been given hints several times as to why she's quite a bitch, and as you've stated, she never starts the fight. Her bitchiness is justified in that everyone around has a tendency to act stupidly.

Ruby nearly exploded her luggage, then Blake points out the SDC's darker side on their first encounter.

Later, to avoid Ruby exploding more things, she gives her a Dust pamphlet, but had no intentions of befriending her. Ruby tried befriending her, causing Weiss to snark back.

Nighttime, the R&Y sisters make a lot of noise, waking up Weiss in the process. And that's pretty damn annoying.

Next day, Jaune tries hitting on her and gets a bit too close for comfort, forcing Weiss to request some assistance from Pyrrha.

Then let's fast forward to the next day, where Ruby wakes up Weiss with a fucking whistle, then unwittingly distract her from class. This culminates into Weiss flipping her shit when Ruby was genuinely trying to be nice.

And finally, Weiss vs Blake, as you've already clarified.

Most of the conflicts she was involved in was clearly started by the other party.