Origin

After separating from Eddie Brock and laying low, Toxin is forced out of hiding during Knull's invasion and bonds with Bren Waters, the son of a Guardsman.

Creation

Bren debuts in King in Black: Planet of the Symbiotes #3 in a short story by Steve Orlando and Gerardo Sandoval. He bonded with Toxin before the beginning of the story. According to Toxin, Knull had no use for him.

Major Story Arcs

King in Black

After Toxin bonded with Bren, he thought of them as best friends, while Bren sarcastically referred to him as his "malignant passenger." Bren definitely seemed to enjoy the new power that Toxin afforded him and used it to become a superhero. While everyone else was battling Knull's symbiote army, Toxin and Bren took on a seemingly supercharged Brood, however, according to the Brood, he was a human who was experimented on by Alchemax.

Alchemax's involvement also means the Guardsman. A Guardsman got involved and fought Toxin for a chance to recover the Brood hybrid test subject, who just happened to be Bren's father, although neither Bren nor his father knew it at the time.

Extreme Carnage

Bren was channel surfing with Toxin, when they uncovered a news story about a terrorist attack at Alchemax. It was actually a fight between Flash Thompson and Phage working on orders from Carnage. Bren is worried about his father, who works at Alchemax, so he suits up and heads there.

By the time he gets there, the fight is over, but he sees his father being wheeled out on a stretcher. His dad is still talking though and assures Bren everything is fine. Toxin, however, is not talking. He had been dragged into the symbiote hive-mind by Carnage, who was fighting him for control.

Thankfully, Toxin was able to defeat him and reconnect with Bren. After giving Carnage the boot, they can only sense one other symbiote, the newly created Silence, bonded to Andi. Those two were regrouping with Flash, who was assembling a team against Carnage, which Toxin accepted an invitation to.

With intel from Flash's friend Hank, who got a job with the Krane campaign, they learned the campaign planned to upstage the President's commemoration of those who died during Knull's invasion. Carnage intended to assassinate Sen. Krane, who was working for the Friends of Humanity. Bren and his new friends showed up to the demonstration to fight off The Life Foundation Five, until the Guardsman could take them into custody. Because Agony and Carnage got away, Flash and Andi reluctantly agree to let Bren stay in the loop despite his youth.

State of Grace

Bren, with the help of Toxin, tracked down Dylan Brock, who was currently bonded to Venom. Dylan was trying to recruit symbiotes awaiting his father's return, but Bren needed his help when he found out employees at Alchemax were being tortured for information about the corporation by an eco-terrorist organization called, NoName. Bren believed they should be spared, and Dylan reluctantly agreed.

Unfortunately, NoName got to Bren and used anti-symbiote weaponry to separate him from Toxin. He was to be the next relative of an Alchemax employee to be publicly poisoned by Alcehmax's own chemicals. Bren was chained up in a pool, which was slowly filled with water poisoned with the same chemicals Alchemax added to a local water supply causing dozens of deaths. Venom, Sleeper, and Toxin tracked the location, and without thinking, Toxin jumped in to save Bren. Unfortunately, the chemicals caused harm to both host and symbiote.

After they were rescued by Venom, Sleeper said they needed to be cured by Anti-Venom, so they searched out Flash Thompson.

Venom War

Bren was watching a pro wrestling live event when Eddie Brock and the other Kings in Black teleported into the ring and demanded to see Dylan and Venom. As Toxin, he swung to Dylan's hideout to inform him about what his dad was doing. They would assemble the rest of Dylan's hive: Normie Osborn with Rascal (aka Red Goblin), Sleeper, and Flexo. At first, they tried to hang back and just watch the live feed, but eventually, they got sick of Eddie's behavior and decided to sneak into Grand Garden Arena to confront Eddie together.

Venom showed up bonded to Spider-Man hoping to keep the peace between the two groups. This irked Eddie who forced the Kings in Black symbiotes to combine into one super symbiote. While Spidey held his own, Bren turned to Dylan as their leader, believing that they should get involved. Dylan finally jumped into action by having Sleeper and Flexo combine into a super symbiote for him to bond to. Eddie refused to hit his son, but Flexo was being secretly manipulated by Doctor Doom. He prepared to fire on Eddie. Sleeper tried to restrain him but was ripped from Dylan's body by Red Goblin (who was being manipulated by Kang) and now needed time to recover.

Toxin spent the rest of the fight keeping Sleeper safe as he recovered. As the fight raged on, they were joined by Agent Anti-Venom. Flash used his powers on Bedlam rending him inert, but he incidentally led a horde of zombiotes, mindless symbiotes that multiply and spread like an infection, into the arena. Eddie combined the Anti-Venom symbiote with his King in Black hivemind connection to cure all the zombiotes. Sensing this, Meridius used Carnage's cosmic weapon, the All-Blood Necro Spear, to reinfect the Eddie and the zombiotes with Carnage. Sleeper and Toxin were immune thanks to Dylan disconnecting them from the codex.

Toxin tried to fight through the carnage zombiotes to get to Dylan, but he couldn't make it. Luckily, Dylan's future self time traveled to the present with a cold metallic symbiote called Eganrac, an anti-venom version of Carnage. With this new symbiote, Dylan was able to use the All-Blood to kill the entire zombiote plague and defeat Meridius. Unfortunately, the Eganrac and the All-Blood started to take each other out, and Venom was forced to abandon Dylan before the gangrene got him too.

S.C.A.R.

After the Venom War, Toxin was taken into custody by SCAR (Symbiote Containment and Rendition), a government agency put in charge of finding symbiotes a new non-hostile planet to deport the symbiotes to. He was separated from Bren, who was sent home thanks to Flash cooperating with the agency.