Asunder Rain The Flames And Thunder

It was the work of a lifetime to catalogue all the animals and plants of hell in a single compendium, but now the scientist's body lies broken and dying with his work buried alongside him. That book is discovered by an unlikely source. A demon boy, who stumbles upon the book encircled by silver birds. The discovery ushers forth a journey that blurs the realms of life, death and beyond. Oh and the birds seem to like him too. https://www.royalroad.com/fiction/197069/asunder-rain-the-flames-and-thunder