Is Z Nation based on a graphic novel?

Yes, Z Nation is based on a comic book. It takes inspiration from the source material to create an exciting TV series.

Another idea for a fanfiction involving 10K in Z Nation is a time - travel scenario. What if 10K somehow got sent back in time to before the zombie outbreak? He could use his knowledge of the future to try and prevent the apocalypse, or at least change some things to make survival easier for everyone.

Yes, it is. Z Nation clearly falls into the science fiction genre with its post-apocalyptic setting and various sci-fi elements.

Sorry?

One idea could be a crossover where Naruto characters end up in the Z Nation world. For example, Naruto with his shadow clone jutsu could be really useful against the zombies. He could send out clones to distract the zombies while the group tries to find a safe place.

Well, 'The Lone Survivor in Z Nation' is a popular one too. It tells the story of a single person who manages to outwit the zombies and other dangerous groups all by themselves. The way the author describes the survival tactics is really engaging.

Survival is a very common theme. Since it's set in the Z Nation world, characters like 10k are constantly fighting for their lives against zombies. Another theme is friendship, like the bond between 10k and his comrades. They rely on each other to get through tough situations.

In a fanfiction, 10K might get separated from his group. He then has to survive on his own in a very hostile environment filled with not only zombies but also other dangerous humans. During this time, he could learn new survival skills and also face some of his inner demons. He might even meet some new allies along the way who help him reunite with his group.

Well, Cassandra's back story is full of hardships. In the Z Nation universe, the zombie outbreak changed everything. She was on her own for a long time. She might have witnessed some really horrible things, like people turning into zombies right in front of her. This would have been terrifying but also made her more determined to live. When she met the group, she was initially hesitant but soon realized that being part of a group could increase her chances of survival. Her past experiences as a lone survivor influenced how she interacted with the group members, sometimes being a bit guarded but also very loyal once she trusted someone.

Survival is a very common theme. Given the post - apocalyptic setting of 'Z Nation', fanfics often revolve around 10k and other characters trying to stay alive among the zombies. They need to find food, shelter and avoid getting bitten.