The depiction of violence can be a tricky matter. As it is able to shock and bring fear upon many, but with the right amount it can give the extra touch. Or lose its effect after a certain amount of time. In Elfen Lied the violence gives us a glimpse in pure and evil violence against other species.
I dare to say that Elfen Lied wouldn’t make such an impact if it hadn’t displayed such disturbing violence. The blood and gore emphasized the horror that was inflicted upon humans who had mutations. Used as puppets and experimental tools, their power could turn against ordinary humans and bring terror to the world. If they weren’t stopped of course. Humans used terrible methods to extract knowledge from the mutated.
In Elfen Lied there was a right amount of violence that made the series acceptable. The overuse of violence can lose impact as the viewer gets used to a certain degree of bloodshed. The repetitive use of gore can be a series’ downfall. But Elfen Lied portrayed violence in the form of injustice and horror, inflicted on those who in general meant no harm. Yes, they were potential threats. Yes, they could release a killing spree. But this fact alone shouldn’t be enough to treat them as slaves and test subjects.
The usage of violence in Elfen Lied was so strong, that the thing you remember about the series, is the extreme depiction of violence. Despite this, it showed two sides to the violence. The ones humans used against the mutated and the mutated against the humans. To some extent one felt more sympathy for the mutated, as they were tortured in unbelievable ways.
Indirectly it showed that the usage of extreme violence upon others, stimulated violence within the ones that were mistreated. Releasing anger and hatred for the ones who mistreated them. It is unclear if the mutated humans wouldn’t use the same amount of violence, if they weren’t pushed to their limits. What it does show, is a situation of action and reaction, which could be prevented if other routes were taken for better understanding the differences.