The Dark Dependents and the Light Grown would often use powerful restrictive spells that they placed on slaves.
The Light Grown uses numerous methods and takes up the power of Vows. This was to be willingly taken by the vowing party as they willingly submit to another.
The Dark Dependents have numerous methods which enslave the other person and are more forceful in enacting theirs.
As the Daughter of Ampelos, Riesling naturally could perform the [Soul-Binding Vine], a constrictive spell that latches and chokes the soul of the constrained one causing great pain and even death should the recipient not fulfill his bargain.
Reisling's eyes widened as such an offer was difficult to pass! However, if Nightwing allowed the Soul Binding Vine to be coiled around his soul, Resiling could ensure that no lies would be made! What mystery was there that Nightwing would be willing to have such bindings?
"You... are willing to take the Soul Binding Vine?"