A Darvand is a child of an angel and a human, usually a male angel and a woman. Darvand creatures appear in Anne Eliza Smith's novel "Seola" published in 1878. Devas (or angels) and Darvands are defined early on in the novel on page 15 and again later on page 64.
Etymology
Darvand, in its original Avestan form 'dregvant' means 'wicked.' It is an ethical appellation of unrighteous persons. Angra Mainyu, the Evil Spirit, is a 'dregvant' or 'darvand' or wicked, as Spenta Mainyu, the Good Spirit, is 'ashavan' or righteous.
Thou Ahura Mazda, dost recognize only two classes among mankind, the 'ashavan' or righteous and the 'dregvant,' 'darvand' or wicked to whatever religion they may belong. Those alone among Zoroastrians, who think good thoughts, speak good words and do good deeds are 'ashavan' or righteous in thy sight. Those who don Sudrah and Kusti, the sacred shirt and girdle, and call themselves the Mazda worshipping Zoroastrians yet think evil thoughts and speak evil words and do evil deeds, are 'darvands' or wicked. Those that profess to be good Mazdayasnians, but whose conduct gives the lie to their profession, are themselves 'darvands,' wicked indeed.