What is "true" domestic violence?

This is really hard to answer without a specific case.

However, I think that, usually the one that ends up hurt the worst is looked at as the victim, and the one hurt least is the perpetrator; UNLESS, it's a self defense case where the girl was coming at the guy with a butcher knife and he ends up hurting her in order to prevent his own death.

There's also the point of having to look at who crossed a boundary line first, and what was the reaction.

In a fight between Brothers...if one lands a punch, and the other does not retaliate. Then the one that got hit is the victim. If he retaliates and punches his brother back, they are both victims and perpetrators. Now, there's also the fact of what lead to the physical altercation. maybe the one that got punched was being very verbally abusive. At that point, he is the perpetrator; When the brother decides to punch him, he crossed a further line, and thus becomes the perpetrator and the other a victim.

It's domestic violence between one, the other, or both. There is no "true". It is, or it isn't.

I ask this because if a relationship is toxic and both parties are at fault for abuse, who is really the victim? I think a lot of domestic violence cases some people miss that.

I quoted the word "true" because in some domestic violence cases, both parties are violently physical hence is why I ask what makes a person a victim. Is it because they refuse to defend themselves. Is it someone who is chronically abused? What if both people are antagonist?

who gives a **** about "true" or even "domestic", why not concentrate on violence of any kind, and doing what you can to end it

Because in the discussion of domestic violence period and for purposes of discussing statistics the variable of the toxicity of a relationship and whether abuse is chronic on both sides needs to be discussed. For example if domestic issues are solved via violence then we need to discuss the underlying factors as to why physical violence is the denominator of toxic disputes. I think in order to end violence all factors that lead up to it needs to be addressed hence the subject title.