One common theme is the search for lost Templar treasures. In many of these novels, the main characters are on a quest to find the hidden wealth that the Templars were believed to have amassed. Another theme is the uncovering of ancient Templar secrets, like their religious beliefs and practices that were kept hidden from the public.
The theme of mystery itself is of course central. Templar mystery novels usually involve a mystery that is related to the Templars' history, like the disappearance of important Templar figures or the meaning behind certain Templar symbols. There is also the theme of adventure, as the characters often have to go on dangerous journeys and face many obstacles to solve the mystery related to the Templars.
Often, there is a theme of conspiracy. The Templars were persecuted in the past, and in templar mystery novels, this is sometimes explored as part of a larger conspiracy theory. For example, that they were framed for something or that there were powerful forces behind their downfall. Additionally, the theme of redemption can be present, especially when the main character has a personal connection to the Templars and is trying to right the wrongs done to them in history.
One common theme is the idea of chivalry. Templars were often seen as chivalrous knights, so in these novels, their actions are usually guided by a strict code of honor. Another theme is the forbidden love. Since the Templars had their own set of rules and regulations, falling in love might be against their order, which adds a sense of drama and tension to the story. Also, adventure is a big part of it. They might go on quests, fight battles, and discover ancient secrets.
One common theme is the search for hidden treasures. The Templars were rumored to have amassed great wealth, so many stories revolve around characters trying to find it.
One common theme is the struggle between duty and personal beliefs. Templars often have to follow the strict rules of the order, but they may have their own ideas about right and wrong. Another theme is redemption. Many fanfictions explore whether a templar who has done wrong can find a way to make amends. Also, the theme of loyalty, whether it's loyalty to the templar order, to friends, or to a cause.
Love against all odds is a typical theme. The fact that they are from opposing factions makes their relationship seem impossible at first. So, the fanfic often focuses on how they overcome these obstacles to be together. For example, they might have to keep their relationship a secret from their comrades. Also, themes of redemption can be present. Maybe the templar is seen as a 'bad guy' in the original story, but through the relationship with the assassin, they start to change for the better. And vice - versa, the assassin might also have some growth in terms of their view of the templars.
In mystery novels, a common theme is the presence of a mysterious or suspicious character. This character might be the villain or just someone with a hidden agenda. Another theme is the setting which can add to the mystery. For example, a spooky old mansion or a fog - covered alley can enhance the sense of mystery. Additionally, the theme of danger is often there. The characters, especially the protagonist, are usually in some kind of danger as they dig deeper into the mystery. It could be physical danger like being attacked or more of a social danger like having their reputation ruined.
One common theme is the search for truth. The detective or protagonist is constantly trying to figure out what really happened, whether it's a murder, a disappearance, or some other mystery. Another theme is deception. There are often characters who are lying or hiding something, which adds to the mystery. Also, justice is a big theme. Usually, the mystery is solved to bring about some form of justice, whether it's putting a criminal behind bars or clearing an innocent person's name.
A theme that often shows up is friendship. Even though they come from different backgrounds, Harry Potter and Simon Templar form a bond in the fanfiction. This friendship helps them overcome challenges. There's also the theme of mystery. The magical world has its own mysteries and when Simon Templar enters it, more mysteries unfold, which makes for an exciting read.
Some common themes in male templar Diablo 3 fanfiction could be heroism. The male templar is often depicted as a heroic figure, fighting against the forces of evil in the Diablo universe. Another theme might be redemption. Maybe the templar has a past misdeed and is on a journey to make up for it. Also, loyalty could be a theme, either loyalty to a cause, like protecting Sanctuary, or loyalty to comrades in arms.
One common theme is the struggle with the templar oaths. In many fanfictions, Trevelyan templars question the strictness of the oaths they've taken, especially in relation to the mages. For example, they might see the mages as more than just threats to be controlled, which goes against the traditional templar view.
I really like 'The Templar's Cross'. It tells a story filled with mystery where the main character uncovers secrets about the Templars that have been hidden for centuries. There are also elements of historical research in it, which makes it not only an exciting mystery but also somewhat educational in terms of Templar history.