One common theme is adventure. Since they are both part of the wizarding world in Fantastic Beasts, many fanfictions involve them going on magical adventures together, facing dangerous beasts or dark wizards.
Newt might be exhausted because of the long hours spent exploring dangerous places and trying to protect the magical creatures. The pressure to keep them safe and the unexpected obstacles along the way can really take a toll on him.
Well, usually when Newt is kidnapped in such fanfictions, it leads to a race against time for his friends to rescue him and uncover the kidnappers' motives. There might be hidden secrets and magical challenges along the way.
You can start by looking on fanfiction websites like Archive of Our Own (AO3). There are often many well - written Newt x Tina fanfictions there. Just search for 'Fantastic Beasts Newt x Tina' in the search bar.
There are various kinds. Some might focus on giving Newt a female counterpart in adventures, while others could reimagine Newt as a female character herself.
There are various types. Some might have Newt hurt in dangerous magical encounters while exploring new realms. Others could show him injured in battles against dark wizards.