I almost get killed by a janitor

The god Tartarus, doesn't have kids with mortals. He hates demigods. But what if he didn't? This story is the story of a young demigod whose father turn out to be Tartarus himself!
For such a powerful demigod, a powerful quest awaits, the almighty Zeus, has a problem, well plenty, but only one that can be fixed by this demigod. Will he?

(Please note that this has not been written after defeating Gaia, it takes place during Mark of Athena & House of Hades, and that this is not about Percy Jackson or the 7)