Stella the Starbeast, properly codenamed S.T. by the FAC, is an Apostle of Ash that resembled a cat-like alien creature. It escaped from defenses against the Tide of Ashes and entered DisCity, where it used its power to create clones of itself in order to hide its true body. One of these clones took shelter with OwO, who gave it the name Stella.
Stella was the first Apostle of Ash to penetrate so far into DisCity and so close to the DisSea, but it was wounded during its battle with the FAC. As a result, Stella developed a strong tendency to approach and provoke crowds with its clone bodies. These clones mostly appeared in densely populated areas of Eastside, and possessed a "quasi-concretization power" that devours human imagination and expels their thoughts into reality. These clones caused considerable chaos and destruction, allowing the main body to collect human spiritual energy to repair its injuries. Analysis by Nightingale and Wynn determined that once healed, S.T. would continue onwards to DisSea.
The FAC was required to quickly terminate the clones and cover up their impacts, but the clone known as Stella was uniquely safe and stable among these clone bodies, allowing it to be observed and studied by the Chief instead of requiring swift termination. Through its interactions with humans, Stella's consciousness changed enough to differ, and ultimately become at odds with, the consciousness of the main Apostle body.
Role
◆ Beyond DisCars
One of S.T.'s clone bodies fell from the sky into the arms of OwO, who adopted it as a pet and named it Stella. While the FAC hunted S.T.'s other clones, the Chief approached OwO to follow and study Stella, who seemed to be an outlier among the other clone bodies -- unlike the rest, it did not outwardly display reality-altering powers, and did not seem aggressive or disruptive. As the DisCars approached and S.T. healed, the rate of clone creation increased, and became more focused on Dillywood, attracted by the high concentration of spiritual energy from the ambitions and dreams of the people present.
At 5 am on N.F. 1.27.113, the Mania levels in Dillywood reached their peak, and S.T.'s enormous main body appeared in Dillywood. The FAC established a perimeter around the district, but the Apostle proved incredibly resilient and difficult to defeat. OwO, Lynn, Deren, Love and Daisy, and the Chief arrived in Dillywood, as OwO believed that returning Stella to its "family" would stop the monsters' rampage. The Sinners fought the monster and its clones, but OwO was put in danger, Stella interposed itself between the girl and the attacker. Immediately thereafter, S.T.'s main body disappeared, with its progeny becoming berserk and upping their attacks to cover its retreat.
The main body reappeared the following day on the outskirts of DisCity, having conjured a full realm of fantasy within an illusory theater. OwO again confronted the Apostle, this time having awoken as a Sinner. OwO and Deren together were able to hold back its power enough for Stella to merge with and take control of the main body. Stella spoke briefly to OwO, and said that it could not fully contain the Apostle; and as it was too dangerous to stay behind, it opened a rift back across the dimensions and disappeared from DisCity.