Quarrelsome and arrogant, teenager Josh Xan received his superpowers when alien parasites invaded Earth during the Bloodlines crisis and attacked him, activating his latent metagene. In the past his half Vietnamese heritage had made Josh a target for bigots and caused him mental pain. Now, the negative mental thoughts he had kept bottled up for years saw expression as a unique form of energy which he could project with shattering force. Under the codename Mongrel, he used his darkforce powers to assist Hawkman and other heroes ending the bloodlines crisis.
Mongrel was not the only young hero who earned superpowers during the alien invasion. The aliens, who drank human spinal fluid, triggered a a related outbreak of metahuman powers among a small group of inexperienced youths. Collectively called the "New Bloods", this group of untested champions joined together as the Blood Pack at the behest of the shadowy U.S. government agency the Quorum, which hoped to use Blood Packs's members to advance its own villainoous agenda. After the Quorum's defeat, Mongrel faded from public view.
Mongrel joined the Blood Pack and was trained by Jade. There last battle as a group was against Solomon Grundy. Superboy-Prime used his heat ray to obliterate all the Blood Pack and the Solomon Grundy version.