|Appearance||Tales of Innocence|
|Japanese Voice Actor||Miyuki Sawashiro|
|Character Designer||Mutsumi Inomata|
The group first encounters Sian and his two dog companions, Cer (ケル Keru?) and Ber (ベロ Bero?), as they are leaving the Regnum Cavern. There, Sian claims to smell Vritra, referring to her reincarnation, Hermana Larmo, who quickly distinguishes Sian as the reincarnation of the Manifest guardian Cerberus. Sian introduces himself before demanding to know where the Manifest is, claiming that since Vritra witnessed the destruction of Devaloka, she should know its location in Naraka.
As the group ponders the situation, Sian grows impatient and demands answers, but Hermana retaliates that she is unaware of its location, which infuriates Sian. He then mentions obtaining the Manifest for the sake of rebuilding an ideal world before confessing that he is a member of Arca, claiming that Mathias is a savior who will lead Arca to this ideal world. Ricardo Soldato berates Sian some, making him uncomfortable. Sian then attempts to take Hermana with him, but the others interfere, initiating a fight. After the battle, Sian exchanges some insults with the group before leaving.
Pursuit in Galpos
Later in the story, Sian is shown before Mathias, apologizing for having failed to capture Hermana. Mathias orders him to continue spying on the group and reporting their activities to her, which somewhat confuses Sian due to his young and naive nature. Mathias explains again, and Sian agrees to her orders. When the group arrives in Galpos, they are informed that a kid and two dogs have ravaged the farmstead, and they quickly determine this to be Sian. They venture into the nearby Galpos Jungle, where Sian is said to live, and eventually come across an old man living in a hut who tells them more about Sian.
When Sian was young, he was abandoned near a temple far from civilization. A few years later, Cer and Ber, who are revealed to be Sian's biological brothers, began showing their demonic nature. One day, a monk decided to rid of the dogs but was brutally bitten to death in the process, leaving Sian to escape the temple and live as a vagabond. Deeper within the jungle, the group locates a memory circle, providing them with more knowledge of their past lives. There, Sian appears with Cer and Ber, again demanding to know the location of the Manifest. Deterred by the group's accusation of him being used by Mathias, Sian stresses that Arca is the only place where the Reborn can be accepted. Sian then grows increasingly defensive as the group attempts to explain the true nature of recent events, leading to another fight with the feral child. Upon losing, Sian claims that he will not be fooled by the group and leaves.
Sian appears alongside Mathias and Thitose Cxarma at Sky Castle after the group learns of Asura and Inanna's fate. It is then that Mathias announces her plan to destroy the world for the sake of eliminating dispute. Sian is shocked to hear her say this and immediately questions her intentions, citing her promise of an ideal paradise. However, Mathias claims that no world is better than a tainted world, prompting Sian to attack her, only to be forced back. When Mathias attempts to use Ruca Milda to activate the Manifest, Sian claims that it is impossible due to the two of them having originally been one. He goes on to say that, without a loved one, the Manifest's power is unusable. Shortly afterward, Ruca unleashes his power, causing the sky-bound castle to collapse. Sian manages to save Ruca and escorts him to the nearby Sania Village, where the rest of the group is. As the group resolves to travel to the Tower of Dawn to confront Mathias, Sian vows to stay and guard the village against Regnum soldiers, having abandoned his role in Arca.
Appearance and Personality
Sian is a young boy with dark skin and blood-red eyes. He has brown hair and a marking on his chest that resembles a dog's skull, while his attire consists of brown, camouflage shorts and a matching scarf around his neck. He wears basic brown sandals and carries a small dagger in a beige belt that wraps around his waist. Personality-wise, Sian is naive and mostly innocent, having been deceived by Mathias into fulfilling her goals. Each time he encounters the group, he seems unsure of himself and the situation at hand, often making hesitant remarks and growling at the group when he feels as if they are not taking him seriously.
In battle, Sian fights with his hands and feet, using his hands in the form of claws and striking the ground from the air with his feet. Sian is always accompanied by Cer and Ber, who are as agile in battle as he is, making it difficult for spellcasters to execute their spells without interruption. Apart from his mystic arte, none of Sian's artes are named in the original version of the game; however, the remake provides him with three named strike artes: Bloody Soul (ブラッディソウル?), Earth Breaker (アースブレイカー?), and Wild Rush (ワイルドラッシュ?). In addition, Cer and Ber's single strike arte is Charge Fang, a charging tackle.
- Like many characters in the game, Sian's surname Tenebro derives from Esperanto, meaning "darkness".
- Cer and Ber are Sian's biological brothers, each of them having been reincarnated from one of the three heads of Cerberus.