A possible plot is that they discover a hidden community that seems too good to be true. They have to decide whether to trust it or not. Joel is skeptical while Tess is more open - this could lead to some internal conflict between them. Also, a story about them finding a lost child and having to decide what to do with it would be interesting. Tess might want to help the child while Joel is more worried about the risks it brings.
One way is to show their softer sides with each other. In the game, they are tough survivors, but in fanfiction, we can explore moments where they comfort each other. For example, after a near - death experience, Joel could hold Tess and tell her how important she is to him. Another way is to introduce external factors that force them to rely more on each other. Maybe a new and more dangerous type of infected appears that they have to figure out how to deal with together.
Another way is through their reactions to new characters. If a new survivor joins them, Ellie and Joel's responses can show how much they rely on each other. They might be protective of their relationship and not want anyone to come between them, which further cements their bond as they face these external threats together.
The Last of Us was not a comic originally. It was first developed as a video game, which gained significant popularity and later inspired other related media, but the comic came later.
The duration of the story in The Last of Us depends on several factors. If you rush through the main quests, it could be around 12 hours. But if you take your time, do side quests, and explore the environment thoroughly, it could stretch to 25 hours or more.