Slug is an Autobot fighter who loves to turn Decepticons into pieces of slag and a member of the Lightning Strike Coalition Force and now the Dinobots, as their tactition. Slug turns into a Triceratops.
Slug and the rest of the Lightning Strike Coalition were Autobots under the command of Optimus Prime, although they visibly chafed under his cautious and conservative approach to warfare. Although ordered to return to base, when leader Grimlock discovered that Swoop was in Decepticon custody, Grimlock ignored Optimus Prime's orders and broke rank to hijack a dropship. The group managed to track Swoop's signal to the Sea of Rust, where they prepared to attack Shockwave's tower. They stormed the base head-on, encountering minimal resistance... until they ran afoul of the multitude of Insecticons swarming Shockwave's installation. They nonetheless managed to muscle their way to Swoop, and released him from a harness he was being held in. At this juncture, Slug asked Grimlock if he wanted to simply spirit Swoop away and report their findings to Prime, or to continue their assault and hope to raze the entire Decepticon operation. Grimlock, realizing they had stumbled unto something big, ordered a retreat, only for Shockwave to appear in person, backed up by innumerable more Insecticons. These enemy reinforcements overwhelmed the Lightning Strike Coalition. Though Grimlock managed to struggle free and engage Shockwave as his teammates were carted away by the Insecticons, the Coalition's leader proved no match for the Decepticon scientist. Once the whole team had been defeated, Shockwave began in earnest his experiments on Slug and the others. All five members of the Coalition were strung up, painfully vivisected, and altered. By giving them new alternate modes, based on alien creatures he had observed through a window in space-time, Shockwave hoped to turn Slug and the others into mindless killing machines for the Decepticons to exploit.
In time, Grimlock managed to escape Shockwave's control, and met back up with his teammates. Slug and Swoop informed Grimlock that the Decepticons' plans revolved around a space bridge tower, where their leader confronted Shockwave. Together, the Lightning Strike Coalition, now calling themselves the Dinobots, held onto their identities and swore to continue protecting Cybertron.
After both Optimus and Megatron had left Cybertron behind, Slug and the Dinobots helped convoys of Autobot ships in escaping the planet, while Decepticon saboteurs impeded these efforts. As one of the last convoys escaped Cybertron's atmosphere, Ultra Magnus's shuttle was downed and crashed off in the distance. Slug was hesitant to come to Magnus's rescue, arguing that he was among many Autobots that thought less of the Dinobots after they had been altered with beast modes. But Grimlock convinced his team to go out and retrieve their comrade nonetheless, so that they could prove to all that they were still Autobots through and through. Upon arriving at the crash site, the Dinobots were attacked by Backbite, one of the long-thought-lost Predacons. The monster managed to down Swoop and capture him, though the rest of the Dinobots were unable to pursue immediately; they first had to contend with Grimlock, who had slipped into a primordial rage upon transforming into his Tyrannosaurus mode.
Slug simmered as the other Dinobots put their brains together to track down their captive teammates, having to be reminded by Sludge that their priority was to stage a rescue mission, and not to simply get revenge on their opponents. Using the computer on Magnus's ship, they tracked its owner to a prison in the Sea of Rust. Though Slug wasn't quite ready to accept that their opponents were the mythical "Forged," Grimlock assured him that previous reports had confirmed their existence. Taking the news lightly, Slug quipped that the prison, seemingly lax in defenses, might be protected by the Forged's "magic powers." The Dinobots still broke in with relative ease, Slug noting that the Forged weren't nearly as tough as the stories made them out to be, and managed to liberate the 'bots held within. Now reunited with Ultra Magnus, the group then fought their way to the prison's roof, where they were confronted by Shockwave's lieutenant, Ser-Ket, and a brainwashed Swoop.
Desperate to win back Swoop's freedom, Grimlock challenged Ser-Ket to a one-on-one fight, waging himself and the rest of the Dinobots against the freedom of their wayward teammate. Ser-Ket agreed to his challenge, and Slug created a fire-ring for them to duel in with the help of the other remaining Dinobots. Grimlock ultimately arose victorious by using his Tyrannosaurus mode's primal rage, and even managed to restore Swoop to his senses with some percussive maintenance. The Dinobots then readied themselves to take their leave, only for Ser-Ket to ambush Grimlock while his back was turned, and carry him up into the skies. Though Slug, Snarl, and Sludge tried to shoot her down, it was Swoop who rescued the Dinobot Commander by taking to the air himself. Ser-Ket was brought down, and Slug watched on as Grimlock skewered her head, deactivating her permanently. Though the ordeal seemed at an end, the Dinobots were then approached by Shockwave.
Though the Dinobots and Ultra Magnus unleashed all of the firepower at their disposal against the new arrival, Shockwave managed to take them all out by strategic use of a force-field and an EMP. While Slug and the others were put under guard in a force-field-enclosed cell, Grimlock was brought to Shockwave's operating theater to be stripped of his sentience once and for all. Slug and Ultra Magnus staged a fight between themselves to trick their guards into lowering the force-field holding them captive, threatening the continued existence of Shockwave's future test-subjects. Slug then trounced the guards, and the Dinobots bashed their way into Shockwave's lab. Together, they then tore Shockwave to shreds. Unfortunately, this turned out to merely be an avatar of the real Shockwave, as the Dinobots learned while releasing Grimlock's restraints. Afterwards, the Dinobots saw Ultra Magnus off-planet, telling him they planned to stay behind so as to continue helping whatever Cybertronians still lingered on the dying planet, as well as continue their hunt for Shockwave.
As the Dinobots managed to find more and more survivors on their dying world, Grimlock took up the role of their king, and was left with the burden of hearing out their many petitions and grievances. Slug interrupted one of these sessions to inform Grimlock that the bodies of the Forged from the attack on New Kalis were ready for him to look over. Some time later, the Dinobots moved to the settlement of Last Spark. Slug became worried when Grimlock and Swoop didn't return from one of their patrols on schedule, but before he could go looking for them, Last Spark came under attack from a group of organic dinosaurs. Slug locked horns with his counterpart, but found that his doppelgänger was stronger than it first appeared. In order to more effectively battle the beasts, the Dinobots swapped opponents, only for the creatures to self-destruct mid-battle. Grimlock later explained that he and Swoop had accidentally released the Dinosaurs while exploring one of Shockwave's abandoned labs, and that the creatures had been created from the same templates that Shockwave had used for their beast modes.
While on an Energon gathering mission, Slug and Sludge felt a planet-wide quake rock Cybertron. After barely avoiding being crushed by the tremor, Slug suddenly found himself re-energized in its aftermath. Both Dinobots then realized that the cavern they were in had been completely restructured by the mysterious event. Unfortunately, this meant the path they had previously taken no longer existed. Slug attempted to muscle his way through the wall that had just sprung up behind them, only to find it immovable. Sludge convinced Slug to instead try and make their way to New Spark through a different path, and ask for help there. As they made their way through the subterranean maze, Sludge heard someone calling for help. Slug volunteered to investigate, only to find that the pleas were coming from a Forged, trapped under some rubble. Against his better judgement, Slug helped the Decepticon free himself under the pretense that he was arresting him. Slug brought Blackout back to Sludge, and told his fellow Dinobot to patch up their "prisoner" to ensure he didn't die before he could face trial. Slug wound up using his fire-breath to cauterize Blackout's leg, then began carrying the injured 'bot as the group resumed its trek. As they attempted to cross a slick and narrow bridge though, Slug slipped and nearly dropped Blackout into the chasm bellow. While retrieving him, Slug injured his leg. With two members of the group now unable to walk, Slug instructed Sludge to go on ahead while the infirm would wait for him to return with help. Sludge complied. As free-flowing energon found its way to Slug, the Dinobot was able to re-energize himself. Blackout's injuries were too severe, however, and the Decepticon expired. Slug resumed heading for the surface, where he found Grimlock among a crowd of other survivors. Before they could all get caught up, an army of Forged came charging towards them, guns ablaze. The Dinobots charged back, only for the battle to be interrupted by a Predacon bursting forth from the underground. The beast was sent fleeing when Sludge finally joined the battle, bringing reinforcements along with him: Arcee, Bumblebee, and Bulkhead!
The Autobots headed for Kaon together, battling their way through the Forged army. But once the Decepticons had been dealt with, the Predacon resurfaced. The Autobots split into groups to head to Kaon, with Slug, Bulkhead, and Firestar leading one group of survivors. Swoop drew off the Predacon when it attacked, allowing Slug and the others to reach Kaon. There, Grimlock announced that Dinobots wouldn't be able to help with Kaon, as they would be building a new city for the survivors: New Spark.
Slug and the rest of the Lightning Strike Coalition deserted their post defending the Ark when they detected strange energy readings in the Sea of Rust. The energy readings were caused by Shockwave's space bridge experiments at the energon lake, and when they arrived, they came under attack by Insecticons and were overwhelmed. Shockwave took the time to experiment on them, giving them primitive dinosaur forms. Slug broke free and trashed the lab he was in, melting a hole in the floor which he departed through. He roamed the caves until he smashed through a door, crushing Kickback and finding Grimlock. Luckily for Grimlock and Swoop, he was able to lead them to where Snarl was being held by Sharpshot. Once Snarl was freed, they sought shelter in an observation post and found Shockwave's logs concerning his experiments on them and the space bridge.
Against Grimlock's wishes, Slug contacted Optimus Prime, who ordered them all back to base. Grimlock refused, instead heading out to destroy the space bridge tower himself, and the other Dinobots later watched from afar as the tower exploded.
- His original name was Slag but was changed to Slug because of trademark issues.
- The line he says to Kickback upon knocking the door on top of him ("excuse me"), is a reference to the same exact line said in the Generation One "The Transformers" Movie.
- Slug and the rest of the Dinobots (excluding Sludge) can be downloaded from the "Dinobot Destructor" pack.
- This is the second new name assigned to a counterpart of Generation 1 Slag; the first was Snarl (as in Animated Snarl and Robot Heroes Snarl, both of whom borrowed the name from Generation 1 Snarl).
- In addition to referring to a round of ammunition or a swift smack across the face, the word "slug" is used by blacksmiths to describe the hot, leftover piece of metal that is punched out when they need to make a hole in something. All of this is rather apt when considering Generation 1 Slag's personality.
- Slug has an Infiltrator body type. As such, Slug's beast mode head is available as a Predator-type component for Infiltrator-class characters in Fall of Cybertron multiplayer.
- Ironically, while Generation 1 Slag was always seen as the surliest Dinobot with the least amount of respect for Optimus Prime, Slug is the first Dinobot to declare the group should contact Optimus Prime for assistance during the assault on Shockwave's Space Bridge, even going as far as to do so without his leader's acknowledgement.