I Am a Demon King, so Raising Snakes Is Normal, Right?

I just traveled through time, and because of my ancient bloodline, the system directly became my little brother! One hundred thousand years after the first disciple he trained came out! The main character feels bored because he can't go out. Until one day, a little snake climbed onto his shoulder and gave him a bite while he was sleeping. Ever since, life is finally no longer boring!