Each is divided down the middle with an awful bone saw and the halves are fused to their mismatched twins with baleful arts. This typically produces two Lichwives--one Lich-Sinister one Lich-Dexter.
The unwilling victim remains alive and can be saved if the lich halves are slain, however, the victim-halves are physically subservient to their evil halves and typically do nothing but scream and beg for mercy.
Damage done to the Lich half is likewise done to the human half.
Allowing the living half of a lichwife to die generally has dire consequnces. Make some up.
-Twice as many actions per round.
-Defenseless or successfully grappled targets may be level-drained.
-Immunity to effects granted by the "stitched" cleric's god--including turning.
-The evil half may modulate the voice of the living half to disturbing effect--anyone hearing the living half's pleas must save or cower in disgust as if affected by Fear.
-Access to all spells of the "stitched"cleric (except those which specifically and exclusively assault evil).
-The evil half may regenerate 6 hp per round by draining life from the good half.