Amelia was dead 3 year ago,not 10, anyway here info about dark one and fallen

Dark one and fallen are always in the dark,if they enter the light,they will disappear and reappear in the dark (for fallen, specifically where they died)

Fallen only visible one day per week in order of Monday to Sunday while dark one ALWAYS appear during nightime or in dark place

Dark one usually friendly to humna (except Lilith) whilq fallen is basically soul,some accept their death while others still in denials

Fallen WILL look like their dead corpse, although sometimes their body elongated because their corpse's limb was pulled apart but still near them

Dark one and fallen (ironically) are immortal

Nobody know about their existence save for claire, Abbie,leira,miss bloomie,Engel and the guard that work as forest ranger in forest of the dead