It Takes Two to Tango

What causes quarrels and what causes fights among you? Is it not this, that your passions are at war within you? You desire and do not have, so you murder. You covet and cannot obtain, so you fight and quarrel. You do not have, because you do not ask.
James 4:1-2

It doesn't matter who started it.

By definition, a fight or quarrel requires two parties, which means there are always two people who covet something they don't have in those moments, not one.

And thus two sinners before God who need to repent.