Rules FAQ

RRG, p. 5 ("Dead Pile"): "A single instance of a unique card in a player’s dead pile does not prevent an effect that would cause the card to enter play directly from the dead pile. This is because such an effect removes the only instance of the card from the dead pile."

Therefore, if there is more than one instance of a unique character in the dead pile (through Heads on Spikes, etc), then Aeron can NOT bring one into play.