Or rather, this is actually a canonically accurate representation of the nonstandard way Eula uses the term "vengeance" - because what she means by it is "paying back" in like and proportional measure. Lady doesn't like owing debts.
Like now hugs here. (Doesn't hurt that backstory-wise she's more or less Amber's adopted sister in all but name...)
It's a pretty major part of her character that she deliberately acts and talks in ways that require some effort to decipher the actual meaning, 'least until you get used to it.