He might try to reason with kaldur. If Nightwing can make kaldur see that what he's doing is wrong or that there are better ways to achieve his goals, kaldur could let him go. Nightwing is known for his charisma and intelligence in such situations.
Maybe kaldur has been brainwashed. He might be forced to kidnap Nightwing by some evil force. The story could then focus on the other heroes trying to rescue Nightwing and break kaldur's mind control.
One common theme could be self - discovery. Since the character is in a new or different form (as a female), exploring her own identity within the context of the story's world would be interesting. For example, how she is perceived by others and how she perceives herself.
No, it's not common at all. Thor is usually depicted as a heroic and noble character in fanfiction. Kidnapping goes against his basic nature of protecting the weak and upholding justice.
I'm not sure of specific 'female kaldur'ahm fanfiction' off the top of my head. But you could try searching on fanfiction - dedicated forums. There are often communities of fans who share and discuss their favorite fanfics, and they may be able to point you in the right direction for ones related to this character.
First, focus on character development. Give your OC a unique backstory, personality traits, and goals. For example, if your OC has a troubled past, it can add depth to their relationship with Kaldur. Second, understand Kaldur's character. Know his values, his Atlantean heritage, and how he interacts with others. Then, create a plot that throws them together in interesting situations. It could be a mission where they have to rely on each other. Also, don't rush the relationship. Let it develop naturally over time through shared experiences and conversations.
One great Young Justice Kaldur x OC fanfiction is 'The Unseen Bond'. It delves deep into the relationship between Kaldur and the OC. The OC is a new recruit with a mysterious past that slowly unfolds as she and Kaldur are paired on various missions. Their relationship develops from mutual respect to something deeper, with well - written dialogue and action scenes that keep you hooked. Another good one is 'Ocean's Connection' which focuses more on the cultural aspects of Kaldur's Atlantean heritage and how the OC, who has an affinity for water - based powers, connects with him on that level.
He might try to engage Slade in conversation. Nightwing is smart and could be looking for a way to psychologically get an edge over Slade. He could be probing for Slade's motives, hoping to find a way to turn the situation around. He might also be stalling for time, waiting for the right moment to make his move.
One common theme is the heroic rescue. In these fanfictions, Max and 99 often use their unique spy skills to outwit the kidnappers and save the day. Another theme could be the emotional turmoil of the kidnapped character, exploring their fears and hopes while in captivity.
You can start by looking on fanfiction websites like Archive of Our Own (AO3). It has a large collection of fanfictions from various fandoms, including Get Smart. There may also be some on FanFiction.net.