A possible way is to have a jutsu that allows the Cerberus to merge with the summoner. When merged, they could perform a super - jutsu that combines the physical strength of Cerberus and the chakra control of the summoner. It would be like a transformation jutsu but with a Cerberus twist.
Maybe the Cerberus in the fanfiction has a special connection to the Nine - Tailed Fox. It could be that they are both from an ancient and powerful lineage. The Cerberus could be a guardian of some sort, and its summoning requires the main character to prove their worthiness, perhaps by passing a series of trials in a mysterious realm.
Cerberus in Naruto fanfiction can be integrated into the story in really creative ways. It could be related to the Sage of Six Paths' legend in some way, perhaps being an ancient creature that was once tamed by him. In some fanfictions, Cerberus might have a connection to the tailed beasts, maybe being a precursor to them. Its appearance in a fanfic can add an element of mystery and danger, as it's not a typical Naruto -verse creature.
Well, in a 'naruto cerberus slayer fanfiction', it could start with Naruto being on a mission in a strange land where the cerberus is causing chaos. He might have to figure out its weaknesses first. Since Naruto is known for his determination and ability to grow, he could learn new jutsus or strategies during the battle with the cerberus. And perhaps there are some side characters that help him along the way, like his friends from Konoha who join him on this unexpected adventure.
Well, it could be a very interesting and unique fanfiction. It might involve Naruto having some sort of connection to Cerberus. Maybe in this story, Naruto has powers or a backstory related to Cerberus. It could be that Cerberus is some sort of mythical being in this fan - made world, and Naruto being his son gives him special abilities or a different role in the Naruto universe that we know. It might also change his relationships with other characters in the series.
Another way Cerberus can fit into the Naruto world in fanfiction is as a spiritual guide. Maybe Naruto, during a near - death experience, enters a spiritual realm where he meets Cerberus. Cerberus then guides him on a journey to discover new powers within himself. This could be related to Naruto's connection with the nine - tailed fox and how Cerberus helps him better understand and control that power.
One interesting Naruto Cerberus fanfiction could be about Cerberus being a secret summon in the Naruto world. Maybe Naruto discovers a hidden scroll that allows him to summon Cerberus and has to train with it to master its powers.
Most likely Naruto would be the main character since it's in his name. But there could also be other characters from the Naruto series like Sasuke or Sakura who might play supporting roles in his quest to slay the cerberus.
It can play the role of a powerful antagonist. Imagine a dark ninja summoning Cerberus to attack a village. With its three heads and fierce abilities, it would be a formidable foe for the protagonists.
You can try searching on popular fanfiction websites like FanFiction.net or Archive of Our Own (AO3). These platforms have a large collection of fanfictions, and by using the search terms 'Naruto is Cerberus', you might be able to find the relevant story.