Echo (エコー, Ekõ) was the most recent incarnation of Duldum created within Noise's subconscious by her own Chain, Duldee. Echo's purpose was to act as a stabilizer of sorts that could protect Noise's mind and heart from shattering from the strain of her Contract - as Noise was neither human nor a true Baskerville but rather an anomaly. Since she had many predecessors, Echo was able to develop her own individuality from the shards of Noise's heart which Echo's predecessors had taken into themselves in order to preserve. After 16 years had passed, Echo still remained void of will and acted only to fulfill her purpose. However, after having encountered Oz during her mission to track down Grim's Contractor, Oz's sympathy and care toward Echo helped provoke change within her that started a development of an individual will of her own. Since then, Echo had acted as her own person and made decisions of her own based on what she believed was right.
Unfortunately, with Duldee's influence over Noise having come full circle, Echo was easily pushed aside so that Noise could pursue what she believed she desired most. Noise was met with failure, prompting further cracking of her heart and encouraging Duldee to take action as she attempted to force Noise into killing Vincent Nightray - who had a strong hold over Noise - in a last ditch attempt to preserve Noise's heart. Echo, knowing that Vincent's death would destroy Noise rather than just ceasing his hold over her, took immediate action and fought for Noise's heart against Duldee. Though Echo managed to kill Duldee and return the memories Noise had lost, the repercussions left Noise on the brink of death. With both her creator and her Contractor dying, Echo's existence was nearing its end. Fortunately, the newly restored Noise allowed Echo to say her goodbyes to her friends before Noise's body crumbled completely and the two left the world of the living together.