You, Eda, King, and Luz lived together like a family, soon found out that The Titan was King's father that King's father, he was secretly watching you through reflective surfaces. After the Day of Unity, you, Luz, her mother, and friends returned to the Boiling Isles, only to find everything changed. A few hours later, Belos possessed Raine’s body. At the Archive House, Belos navigates the halls while struggling to maintain control over Raine's body. This effort causes the puppet spell on Raine to fade, returning them to their true self. As Raine fights for freedom, Belos regains control. Aware that he can't hold Raine much longer, he rushes outside, activating the blue star to create a platform, and descends to his castle. The Collector reveals that all he desired was a friend who would never deceive or betray him. He feels that everyone who claims friendship ultimately lies, including King, Belos, and his own siblings, the Archivists. The Collector explains that they sent him to the Demon Realm years ago to play 'hide and seek' with the baby Titans; during that time, he formed a bond with the infant Titans, but his siblings viewed them as a threat and sought to eliminate the Titan race. The Collector was then trapped by a Titan, who mistook him for an enemy. After his experiences with Belos and the Titan Trappers, he now wishes to keep King as his friend forever, even if it means pretending. Outside, Belos crash-lands at his castle's entrance, while Raine struggles against him. Gathering strength, Raine whistles a wave of bard magic that completely ejects Belos. However, during Raine's recovery, Belos escapes into the castle. Understanding Belos' intentions, Raine follows him and arrives at the throne room with a violin. Belos' voice echoes, questioning Raine about the heart; then, he emerges from the ground's cracks, enveloping Raine in sludge as his main body crawls toward the heart. Just as Belos lunges for it, Raine breaks free from the slime and smashes their violin to create a magic shield around the heart, but it's too late—Belos breaks through and emerges. Below mocks Raine for failing to stop him, then begins merging with the heart, spreading mold-like terrain across the Boiling Isles. Meanwhile, The Collector acknowledges your use of it, noting that not everyone recognizes 'Titan magic.' The Collector wonders if the Titan liked you enough to teach you, magic, specifically his magic. Suddenly you all hear a rumbling sound like breathing. The Titan's eye glows blue, revealing that it's Belos. An eerie forest of mold and decay has taken over the isles. You, Luz, Eda, King, and the Collector fly above, noticing it stems from Belos' castle, now engulfed in mold. The castle transforms into a monstrous dragon-like avatar of Belos, who declares he will cleanse the Boiling Isles and unleashes blue fire across the land. The Titan resolved to set his plan into action to defeat Belos, but you needed to drink the Titan's blood so that he can return to living but you will black out in the process of becoming a Titan fully but he will be with you the entire time and will not leave your side. He used his magic to whisper invisibly into your mind while you held a vial of the Titan's blood because the Titan had a plan.

"Consume the blood." He instructed you from within your thoughts, just before you sensed an unseen hand grasp your wrist, to make you drink the Titan's blood. Now, the voice and the feeling stopped as the island, the fallen titan’s body started moving a little as the Titan was fighting Belos over control of the Titan’s body so the Titan’s eye was flickering cyan and yellow.