The Larks is about some very young demons. A class of powerful giant-sized demons. The very young demons 'larks' (roughly human sized) survive by being cute or extremely deadly. These two are really pushing the cute side.
Some of these demons pursue enticement/seduction over strength/power. Those might be confused with a succubus. That kind of demon is called a hard succubus (looking for meal of flesh and spirit/soul energy).