Brother's Blood and Aggro damage

Name: Brother's Blood
[BL:C2, LoB:C]
Cardtype: Combat
Discipline: Sanguinus
Requires a ready Blood Brother of the same circle as another one in combat.
[san] This vampire can burn his or her own blood to heal or prevent destruction from damage taken by a member of this circle in combat.
[SAN] Put this card on this vampire. The vampire with this card can burn his or her own blood to heal or prevent destruction from damage taken by a member of this circle in combat. A vampire may have only one Brother's Blood.
Artist: Durwin Talon

Situation: Larry burns his last blood to get intercept to block a action. He blocks successfully, with 0 blood. Al-Munthatir play Domain of Evernight and OtH, doing 2 aggro prerange to Larry. Jerry plays Brother's Blood, and burns one to prevent a point of aggro damage.
Question: As Jerry is not in combat, does that mean he takes agro? Or does it mean he can burn blood to prevent both aggro and normal damage?
Thanks

Brother's Blood does not prevent damage. It let's another vampire not in combat burn blood instead of the one actually in combat. In your example Larry takes 2 agg, first one will send him to torpor and second would burn him. At this point Jerry can use Brother's Blood to burn one of his blood to prevent destruction of Larry. Jerry can do nothing to first point of agg received by Larry because it can not be healed, and is neither burning Larry yet.