The information in this article is from the fan game The Silver Lining and is therefore not canon.
Aria was a druidess and sister of the Arch Druid. Aria was kidnapped by some force the Druids could not see, and in captivity, she passed from the world. After many years, because she was a noble druidess, and because he missed her, the Arch Druid honored her memory by placing a painting of her inside of his tree house.
Behind the scenes[]
Aria was likely kidnapped by the Black Cloak Society, and may have been the mother of Valanice (unofficial) before she passed away. If not Aria, it may have possibly been Fand. But then again the Nature Spirit suggests that Valanice is one of her lost children, that she has the Druid blood of her people, which would suggest she is from the heritage of the Druids of the Isle of Mists.