Dragonsbane

Children purchased in their youth are involuntary subjects of a dragonblood transfusion, which gave them unexpected results where they developed adaptive imperviousness. They'd be unstoppable.

Ven Yashke is a boy genius who's about to attend Harvard Medical when a mysterious woman arrives at his home, offering to share information regarding the sudden death of his parents. He suspects they were murdered, but nobody believes him except for her.

But there's a kicker.

He must help her take down the facility running these illegal dragonblood tests, but the facility is through a portal to a whole different world, one that he's been to before without even knowing.

He wonders what lengths he would go to in order to get the answers he seeks.