We don't really know for sure without more context from the fanfiction itself. But they could be two friends, or perhaps they are characters from a particular series or universe that the fanfiction is based on.
Well, Antonio might use his courage and wits to track down where Brett is being held. He could face many obstacles like dangerous kidnappers or tricky traps. Maybe he has some special skills or friends that help him in this rescue mission.
Fanfiction.net is also a good place to look. There are many fans who post their works there. However, the search function might be a bit trickier sometimes. You may need to use specific tags related to the characters like 'Brett', 'Antonio' and 'Chicago Fire' to narrow down the results.
Some fanfictions could focus on their backstories. For example, a story that delves into how Antonio got into firefighting and how Brett overcame her initial fears in the job. Then, it could show how their different paths cross at the Chicago Fire department and how they gradually become important to each other, whether it's as friends or something more.
Since I don't know the details of the 'kaiba saves a kidnapped tea' fanfiction, it's hard to give a precise summary. However, it could start with Tea being kidnapped by some unknown enemy, perhaps someone who wants to use her to get to Kaiba or has a grudge against her. Kaiba then discovers her disappearance and embarks on a dangerous journey to find her. Along the way, he may encounter allies or more foes, and there could be a lot of suspense and action as he tries to free Tea from her captors.
The kidnapper's motive could be revenge against Kaiba. By kidnapping Tea, they know they can draw Kaiba out and make him suffer. Maybe Kaiba defeated this person in a duel before and this is their way of getting back at him.
Her close friends at the firehouse, like Casey or Severide, could be great allies. They've always been there for her, and during her pregnancy, they could offer practical help like covering for her shifts when she's not feeling well or giving her advice on dealing with the pregnancy while working. Stella could also be a strong ally as another female in the firehouse who can understand the unique challenges Brett might face.
The plot might start with Spencer being kidnapped by some unknown villains. Aaron, who has feelings for Spencer, is devastated. He immediately starts investigating, using his skills and connections. As he gets closer to finding Spencer, the tension builds. When he finally rescues Spencer, there's a moment of intense relief and joy. They share a passionate embrace, and from that moment on, their relationship blossoms into a beautiful romance. There could also be sub - plots, like Aaron dealing with his own insecurities about his feelings for Spencer during the rescue mission.
Love and romance are quite common themes. Writers often explore how Margo and Antonio might fall in love, the obstacles they face in their relationship, and how they overcome them.