The hydra of lerna was slained by the great Hercule, as the legend has it.
But the truth is she still lives, hiding in the shadows, waiting for her time to come. For 2500 years the hydra of lerna survived by infecting people's body, switching host when the human gets too old. When she grows strong enough she divides her soul, making an other 'head' in an other human. Now in 2019, with 8 heads spread across the earth and 8 billion of people to feed upon, she has almost recovered her past strenght and is about to go on a rampage once again.
While her movement become more bold, the Hercule descendant have come to know of her existence. Hercule never believed in the hydra's death and formed a group in case his doubts were founded. After so much time, traditions became history and the majority of his lineage is considerably weaker. But nonetheless they will have to fight because the future of the world depends on it.
Hydra of Lern :
At most, she can have 9 heads. Each head act independantly but they are always linked so if a head die, the others know it instantly.
The first head has the power of regeneration and maybe more, since she is the "true head" she is the more powerfull and the more secretive of them.
The second head has the power of metamorphosis, she usually transform her right arm into something sharp to cut her preys.
The third can become invisible, the fourth can fly, the fifth can predict a bit the future, the sixth has her senses extremely sharp, the seventh can duplicate herself for a while and the eight has a lethal venom.
A host doesn't know that it is infected. He is not conscious while the head take over the body. But every host become inevitably fond of reptiles and moreover of snakes.
Nagi Kusa, host of the second head :
In Tokyo, Japan. Nagi Kusa is a brilliant student, she's studying reptiles at the tokyo faculty.
Only child, she likes cookies and...snakes. She doesn't know why but she has developed an interest for human blood along the years. Little did she know that once a week her body is taken over by the hydra's second head. Before, the hydra was acting as a lost child to lure her preys. Now she uses her womanly charm, it's way more efficient.
First ideas :