Tesseract is regarded as one of the most powerful Seed warriors of Halcyon, as he possesses the power to combine and share the strength of an infinite number of his alternate-dimensional counterparts.
Recognizing Tesseract's power, Thanos kidnapped him and had him brainwashed. He achieved this by implanting Tesseract with synthetic nerve cells. These controlled his will and caused him to believe he was loyal to the Acheron Empire. Acting on their own initiative, Seed Nineteen rescued Tesseract. They managed to narrowly escape to a lower dimension, that of Earth 1610. There they found themselves in Earth's New York City. After a misunderstanding led to a confrontation with the Fantastic Four. Tesseract was again captured by Thanos' forces led by his son, Gallowglass.
After pursuing Thanos' forces back to their dimension, Invisible Woman defeated Gallowglass by turning his own volatile powers against him. The ensuing explosion destroyed Gallowglass' ship. The Fantastic Four escaped unharmed with Tesseract, but were stranded on the Acheron-controlled planet of Pyx in the city of Ironwater. There Susan Storm, Reed Richards and Dreamcatcher brought Tesseract to a Seed hideout within the city and attempted to remove his neural implants.
The Fantastic Four and Seed Nineteen were then brought to Earth and forced to battle Ronan The Accuser, Thanos' other son. Tesseract was revived by Dreamcatcher and fought Ronan with his dimensional abilities. However, Tesseract was in a weakened state as a result of his ordeal and was eventually defeated by Ronan. Ronan is ultimately defeated when Reed Richards has the idea to use Dreamcatcher's powers to combine the powers of both the Fantastic Four and Seed Nineteen. After this Tesseract returns with Seed Nineteen to liberate Pyx. Later, when Reed Richards constructed the Cosmic Cube. Tesseract led the Halycon infiltration team that infiltrated the Baxter Building to seize the Cube. Before they could do so, the Cube defended itself throwing up a force field that froze all within it. Richards freed Tesseract and his team from the paralysis. The Halycons fought and subdued the Four, but Tesseract admitted that he was reluctant to harm the Four considering what they had previously done for him. Before they could depart with the Cube, Richards used his mental control over it to teleport Tesseract and his team away.
Powers & Abilities
Tesseract can channel the power of his alternate incarnations across the multiverse to grant himself great levels of strength, durability, speed and reflexes. He focuses each incarnation over his body to increase the amount of force he applies to striking, as if they were existing in the same place as he is when attacking. He can also create a pulsing beacon capable of gaining the attention of his comrades.