Hydron (ハイドロン Haidoron) was the Prince of Vestal, leader of New Vestroia and commander of the Vexos. He was then the new leading Subterra brawler for the Vexos, replacing Gus after he and Spectra left the Vexos. It is revealed in "Facing Ace" that he possessed the petrified statues of five of the Six Soldiers that saved Vestroia: Runo's Tigrerra, Julie's Gorem, Marucho's Preyas, Shun's Skyress, and Alice's Hydranoid. His goal was to "complete his collection" by getting his hands on Dan's Drago.

In "An Heir to Spare" Zenoheld became angry with him for not retrieving the Phantom Data, and punished Hydron with The Agonizer. Later on, Hydron dreamt of Lync and Volt telling him that he should be the new King, not Zenoheld. He then challenged Zenoheld to a brawl, and lost. Although, was able to defeat Farbros, and halve Zenoheld's Life Gauge. He was then thrown in a prison cell along with Gus, thus proving that Gus was still alive.

He was able to escape when Gus tricked him into starting a brawl inside the cells by calling him a lapdog, which angered Hydron, thus releasing Dryoid and Rex Vulcan who, upon release, broke the cells and allowed both Gus and himself to escape.

He then fought alongside the brawlers to defeat his father once and for all, but it appeared he may have died in the process (when the Alternative exploded). Just before the explosion, Hydron looked up and said: "Volt...Lync...I'll be there...soon." Which must mean that the "dimension" that he sent Volt and Lync to is the Vestals form of the afterlife.

It is unknown whether he survived with Dryoid and came back to find Volt and Lync, but, more likely, it is probable that the above quote was referring to the fact he was about to die and join Volt and Lync in being dead.

(Source: Bakugan Wikia)