Sister?!

He survived Tartarus alone but will he make it through school? Nico di Angelo knew about the Egyptians before the others and now he has to pay the price by keeping tabs on them and going to school.
After Blood of Olympus (BoO) and after The Serpents Shadow and after the events in the Crown of Ptolemy in Demigods and Magicians.
First book in a series.
Picture by: InfiniteCity ( who happens to my one of my favorite devianters if not my favorite one )
Picture found on:
https://www.deviantart.com/infinitecity/art/Here-s-your-HAPPY-MEAL-377810049?comment=1%3A377810049%3A3670249372

Disclaimer: I don't own Kane Chronicles or Percy Jackson/Heroes of Olympus
That title belongs to Rick Riordan