The Blackwood Brides

"The Blackwood Brides" is an unconventional story of marriage. Roslind, Laurel, Melati, and Thea. all four of them become brides to a mysterious man who is considered to be an immortal creature. He has reached the age of 1000 years. The man, known as "An Oldman of Blackwood," is also believed to have the power to grant eternal beauty to women, and because of this, many women voluntarily choose to become his servants and live with him in the midst of the forest.

In the passing of time, numerous women arrived at the "Blackwood" forest to obtain eternal beauty. They didn't mind becoming servants of the Oldman for several years as long as they got what they desired.
Roslind, Laurel, Melati, and Thea approached the "An Oldman of Blackwood," but unlike other women who arrived and were made servants, they were instead chosen as brides.

What makes them considered special?