Feeding the Reaver is a gameplay mechanic featured in Legacy of Kain: Defiance, whereby Raziel or Kain could forgo sating their own hunger in favour of 'Feeding the Reaver', which served to fill Reaver charge and enable Charged Attack and Reaver Spell.
In Legacy of Kain: Defiance, Kain and Raziel's versions of The Reaver (The Reaver and Wraith Blade respectively) were able to drain small amounts of life-force (Blood or Souls respectively) from enemies when attacking them and this energy contributed towards the filling of the Reaver Charge Gauge. The amount drained increased as Kain or Raziel utilised more complex and elaborate combos or special moves. In addition, when an enemy was in the waver state (indicating they were ready for feeding) Kain/Raziel could choose to "Feed the Reaver", instead of themselves, impaling the enemy with the blade and allowing it to consume the Blood/Soul of the Enemy and giving the Reaver Charge Gauge a large boost.
The nature of Feeding the Reaver bears some strong similarities to the 'Reaver Arousal Coil' shown in Soul Reaver 2; both mechanics are a way of the Soul Reaver 'feeding' itself, but the resulting effects are subtly different:- Soul Reaver 2's coil is only filled by 'fully' consuming souls of enemies and the wraith blade then does more damage the more filled the coil is. When completely filled, the coil then drained Raziel's Soul Spiral, rather than the beneficial effects seen in Defiance . Some fans have attempted to connect Soul Reaver 2's coil to Constrict - an ability gained by Raziel in Legacy of Kain Soul Reaver, but inexplicably absent from Soul Reaver 2.