It might be a single person on a quest. In a story about a treasure hunt, the main character is the one following the 'hot or cold' clues to find the hidden treasure all by himself.
The main characters in 'Cold Equations' are Marilyn and Barton.
The 'hot or cold' short story could be about a person looking for something. For example, in a game where a hidden object is either in a 'hot' (nearby) or 'cold' (far away) area. One day, a little boy was playing this game in a big house. His friends hid his favorite toy. As he started searching, when he was close to the toy's hiding place, his friends would say 'hot' and when he was far away, they said 'cold'. Finally, he found his toy in the 'hot' zone under a big chair.
Since I haven't read the story, it's hard to say for sure. It might be a lone traveler or a group of scientists. The main characters could be those who are forced to endure this extremely hot environment for some purpose, like to find a hidden treasure or to conduct research in a dangerous but interesting place.
I don't know as I haven't read the novel. But they could be diplomats, military leaders, or spies from the countries involved in the Cold War.
Maggie is another important character. She is a strong - willed woman who is trying to hold on to her marriage to Brick. She has desires and is constantly trying to get through to Brick.
I'm not sure if there are new characters specifically in the 'Hot and Cold' part after the main story. It could be possible though.
The following are some recommended short female protagonist novels: 1. "The Ice Woman's Favorite Husband (Single Public Harm)": The female protagonist is a man in the world of female idols. She is proficient in martial arts, cold and heartless. She likes excitement, but her heart is hot. This novel might meet your requirements for a hot and cold female lead.
The main characters are the pilot and the stowaway girl. The pilot is in charge of the spaceship and has to follow the strict rules of the cold equations. The stowaway girl is an accidental addition to the ship's manifest, she boarded without realizing the consequences her presence would have on the ship's mission.
There's no way to tell who the main characters are in 'cold city story' without more information. They could be anyone from a struggling artist trying to make a name for themselves in the cold city to a detective solving crimes in the frigid urban streets.
One main theme is the inevitability of fate. The stowaway's fate is sealed by the laws of the spaceship's operation.