Who could be the main antagonists in 'Torchwood: Owen Gets Taken by the Rift' fanfiction?

One possible plot development could be that the team at Torchwood desperately tries to find a way to bring Owen back from wherever the rift has taken him. They might search through old Torchwood files and artifacts for any clues on how to reverse the rift's pull.

It could be some of the nobles in the kingdom who are not happy with the idea of Rapunzel having a baby so soon. They might fear that the baby will disrupt the line of succession or cause political unrest. So they try to undermine Rapunzel and Eugene during her pregnancy, creating all sorts of problems for them.

The monsters native to Tartarus could also be antagonists. These could be huge, grotesque creatures that have never seen the outside world. They might attack Percy on sight, seeing him as prey. Some of them could be powerful enough to even give Percy a hard time, especially if his powers are weakened in Tartarus.

One common theme is survival. Given Owen's often - precarious situations in the show, many fanfictions explore how he manages to survive against all odds. For example, in some stories, he has to deal with life - threatening alien encounters alone.

Perhaps it could be a group of bullies from Issei's school days. They used to pick on him and now he's coming back to make them pay.

One potential antagonist could be those within the village who oppose Naruto's relationships. They might see his harem as a threat to the traditional values of the village and try to cause trouble for Naruto and his partners.

It could be some hidden members of Naruto's family itself. Maybe there are relatives who have been manipulating things from the shadows and their actions led Naruto to believe he needs to take revenge on the family as a whole.

Maybe the hidden organizations within Konoha that work in the shadows. They could have been involved in some plot against Naruto that led to his decision for revenge. They would be the ones trying to stop Naruto from exposing their secrets and exacting his revenge on the village as a whole.

I'm not entirely sure as I haven't read it specifically. But generally, in the Torchwood universe, it might deal with the rift and the strange phenomena and battles associated with it. It could involve the Torchwood team facing off against alien threats that come through the rift.

It could be a rogue group of Shinra scientists. They might be obsessed with power and see Cloud as the perfect subject for their unethical experiments. They don't care about the consequences for Cloud or the world at large, just their own thirst for knowledge and power.