Another theme is the idea of forbidden love. It could be that the two characters are from warring factions, different social classes, or there are other external factors that make their love not only difficult but also dangerous. This kind of situation often leads to high - stakes drama and a love that is both intense and fraught with peril.
One common theme is forbidden love. It could be love between two characters from feuding families or different species, like an angel and a demon.
Obsession also plays a big role. Characters can become overly obsessed with their partners or the idea of love. In 'Black Swan', the main character is obsessed with being the perfect swan queen, which ties into her complex relationships. It can lead to self - destruction and harm to others.
Another theme is often betrayal. This can be a complex form of the dark side of love. Maybe one character betrays the trust of the other in the name of love, like hiding important secrets that end up causing a rift in their relationship.
A lesser - known but great 'dark and dangerous love fanfic' is 'Captive Prince' by C.S. Pacat. It's set in a fictional and rather brutal world, and the love that develops between the two main characters is full of challenges, power dynamics, and a sense of danger that keeps the readers on the edge of their seats.
Power and domination are common themes. Dark Eldar are always seeking more power in their society which is highly competitive. So in fanfics, you often see characters vying for positions within their Kabals or cults.
One common theme could be angst. It might involve the characters going through difficult emotional turmoil. Another could be some sort of mystery or suspense related to their relationship. For example, a hidden past that affects their present connection.
Jealousy is a common theme. In a dark love story, characters might be overly possessive and jealous of their loved ones, which can lead to conflict. For example, in 'Wuthering Heights', Heathcliff's jealousy over Catherine's marriage drives him to seek revenge.
One common theme is obsession. In a dark love story, the characters are often obsessed with each other in an extreme way. For example, in 'Fifty Shades of Grey' (although it has some controversial aspects), Christian Grey is obsessed with Anastasia Steele, which drives many of the actions in the story. Another theme is sacrifice. A character may sacrifice their own well - being, values, or even their life for the love they feel. The third theme is secrecy. The love may be hidden due to various reasons, like in 'Romeo and Juliet' where their families' feud forces them to keep their love a secret, adding a layer of darkness to their relationship.
Sacrifice, but in a twisted way. Sometimes in dark love stories, a character might sacrifice their own values, morals or even their life in a way that is not noble but rather a result of their dark love. For instance, a character might sacrifice their integrity to be with the one they love, even if that person is not good for them.
One main theme could be fear. The 'deep' and 'dark' elements often evoke a sense of the unknown and things lurking in the shadows, which can be quite frightening. Another theme might be mystery, as such a title implies there are secrets waiting to be uncovered.