A group of sneaky Oviraptors could also serve as antagonists. They are sly and always trying to steal the eggs of the herd that Bron and Littlefoot's mother are protecting. They use their intelligence to outsmart the herd most of the time, until Bron and Littlefoot's mother figure out a way to stop them once and for all.
Maybe in the fanfic, Bron and Littlefoot's mother team up to protect their herd from a new and powerful predator that has entered their territory. They could use their unique skills and knowledge to outwit the predator and keep everyone safe. For example, Bron might use his strength while Littlefoot's mother uses her intelligence to find the predator's weakness.
Well, in some 'littlefoot x bron fanfic', they might form a strong friendship. For example, Bron could be teaching Littlefoot some new survival skills that his herd doesn't know. And Littlefoot, in turn, could show Bron some fun games that he used to play with his friends. It could be a really heart - warming story of two different characters learning from each other.
First, you need to know the characters well. Research about Littlefoot and Bron, their personalities, strengths, and weaknesses. Then, come up with an interesting plot. It could be something like a journey they take together or a problem they have to solve.
Perhaps a group of anti - technology extremists could be the main antagonists in an Ultron fanfic. They see Ultron as the symbol of all that is wrong with technology and are determined to take him down, no matter the cost. They might use their own advanced, but more rudimentary, technology to fight against Ultron. This would create an interesting contrast between Ultron's high - tech abilities and their more basic, yet effective, methods.
Littlefoot, who has been through many adventures in his life, brings his experience to the story. Shorty, who might be newer or have different perspectives, challenges Littlefoot in some ways. Together, they form the core of the fanfic, and their interactions drive the plot forward whether it's a story of friendship, discovery, or facing challenges.
It could be Lila. Since she is always causing trouble in the series, in a Nathalie - centered fanfiction, she could target Nathalie as well. Maybe she tries to frame Nathalie for something to get closer to Gabriel or to get rid of Nathalie who she sees as an obstacle to her plans.
It could be an evil ninja who wants to stop Kakashi from meeting his mother. This ninja might be from a rival village and fears that Kakashi will gain some powerful knowledge or ability from his mother that could be a threat to their plans.
The main antagonist might be a dark sorcerer. This sorcerer has put a spell on Spyro's mother long ago, trapping her. He doesn't want Spyro to find her because he fears that together they will be strong enough to break his power. He uses his minions to try and stop Spyro during his journey to find his mother.
A rival medicine cat from another Clan might be the main antagonist. They could see Alderheart as a threat to their own status or the well - being of their Clan. So they might use dark magic or some underhanded tactics to bring about his death.
Vilgax could be a great antagonist. He could hack into the gaming systems to try and defeat Ben in a virtual world where the rules are different. He might use his advanced technology to create digital versions of his minions to attack Ben.