Grimdark, as the grimmer and darker sort of fantasy currently very much in fashion has been dubbed, can often have lots of horrid things within. Rape, murder, torture, pain, woe and anguish abound.
Human history (and, sadly, the human present in Syria, Iraq and elsewhere) reveals that mankind has a quite remarkable capacity for inflicting tremendous pain upon itself. At the same time, it’s worth recalling even despicable groups can have a good member (Schindler for the Nazis, for example). Brutes can occasionally show clemency, just as kind men can sometimes erupt with rage.
The strength of the rule of law is critical to considering widespread levels of violence. The Romans were not exactly soft on crime, but the Roman legal system was pretty advanced for its time. Stability and low crime rates were important for the Empire, because stability made people feel more confident, happier to trade and spend, and less likely to hoard money ‘just in case’ something terrible happened. The economy worked well, everyone had a stake in peace, and those who tried to rebel got crushed by the Roman army. For a long time Roman authority was strong, and this worked.
But when the Western Empire collapsed, power ended up being devolved to such small levels that there was barely even the pretence of law and order. Brutality replaced civility, as proven by charming games such as nailing a cat to a tree and headbutting it to death. (I am, sadly, not making that up. The excellent By Sword And Fire, by Sean McGlynn, is really worth buying for a good look at cruelty and clemency in the medieval world, particularly warfare).
Lots of what went on in the medieval era was pretty brutal, and we would consider a leader who commanded such things (including the massacre of prisoners who surrendered on condition they be allowed to live) war crimes. But today’s tyrant was yesterday’s hero. People in villages, towns and cities welcomed a strong ruler. There was no police force, so when criminals were caught harsh measures were approved of and often reassured the people. In war, there was a conflict between brutality and mercy.
The Black Prince had a fearsome reputation, and he deserved it. But this cut both ways. People would often not surrender to him, simply because they preferred to fight (and perhaps die) to entrusting themselves to his care. By contrast, Henry V adopted a milder approach when he conquered much of France in the 15th century.
However, a reputation for being meek and weak could lead to problems. If every surrender is accepted then what penalty would there be (for example) for those rebelling against their lawful king? In the medieval era the lion’s share of a king’s duty was to be the chief warrior of the realm. His position depended upon being strong and being perceived to be strong, and a show of weakness could prompt rebellion, with ambitious rivals taking a tilt at the crown.
Not to mention the fact that if enemies were left alive to fight another day, they might be victorious next time, and not return the merciful favour.
It’s easy to look back and consider the medieval era to be thoroughly uncivilised and savage, but there were rational causes behind the cruelty sometimes enacted. In the same way, a surprising degree of mercy could sometimes be shown. It’s hard for us, with long-term nation-states, international law and well-established domestic justice systems, to put ourselves in the shoes of someone who lived almost a thousand years ago. Back then there was no police force, practically no disease could be cured by medicine and countries (most notably England and France) were just beginning to centralise power and impose order.