The Embrace is process by which a mortal is turned into a Kindred, called a childe, by another vampire, known as the sire. The vampire drains the subject completely of blood, then - at the point of mortal death - gives the mortal some of her own Vitae. The mortal then dies and becomes one of the Kindred. As a neonate she starts with a Blood Potency of 1, and a soul forever scarred and damaged.
In Vampire: The Requiem First Edition, the Embrace took a considerable psychological cost, leaving the sire mentally drained; mechanically, this was represented by the loss of a Willpower dot. Too many Embraces over a short period could leave a sire too feeble minded to function properly. (VTR: Vampire: The Requiem Rulebook , p 20)
In Vampire: The Requiem Second Edition, the Embrace further scars the vampire's soul, costing a dot of Humanity instead of Willpower: Unlike diablerie, where the victim is just another monster, the Embrace propagates the parasitic All Night Society and its endless cycle of death.