Zaun's Sump. Despite such humble origins, Zac has grown from primordial ooze into a thinking being who dwells in the city's pipes, occasionally emerging to help those who cannot help themselves or to rebuild the broken infrastructure of Zaun.is the product of a toxic spill that ran through a chemtech seam and pooled in an isolated cavern deep in
|"The angrier you get, the more this is going to hurt... " — Zac|
Zac was created in Zaun as the Zaun Amorphous Combatant, a synthetic construct of ooze with the ability to react to nearby stimuli and emotions, as a project by Chem-Baron Saito Takeda to create an obedient super soldier who could resist injury and access spaces normal humans couldn't. The blob eventually escaped and stayed in a sump pool, where it reacted to Zaunite children throwing stones at it by throwing them back, causing rumors of a "Returning Pool" known among the dwellers of the sump. Several alchymists travelled to the pool to test its psychotropic properties, finding that treating it well made it respond with childlike joy, but causing it pain resulted in it retaliating and killing several personnel.
One married couple of alchymists dissented against Takeda's project and saw the blob as a sentient being and gave it the name Zac. The couple tried to vouch for Zac's rights to the organization, but were ignored. They taught Zac about morality and how to be good, but the other alchymists experimented with his empathic senses by performing cruel experiments around him which made Zac feel negative emotions. Refusing to tolerate any more unethical treatment towards Zac, the couple helped him escape during Zaun's Progress Day memorials by storing him in a septic tank and moving him to a faraway part of Zaun. When Takeda found out, he sent his soldiers to search for them. The couple initially wanted to set Zac free, but he wanted to stay with them due to the kindness they showed him, so they happily accepted him and adopted him as their son.
Zac and his alchymist parents went into hiding in a remote part of the sump. As they changed their appearances to avoid recognition, Zac learned how to talk by mimicking their voices. Living with them for many years, they taught Zac about the beauty of the world of Runeterra, but also how it could be cruel sometimes with some people having malice in their hearts, but he remained optimistic and continued to do good deeds. He leisurely roamed Zaun through the small spaces he could travel through, but tended to get overwhelmed by the nearby Zaunites' emotions. He often acted upon his emotions, helping fight against bullies and doing good deeds for Zaunite citizens, but his negative emotions would cause him to destroy entire buildings. The rumors of Zac's sightings were picked up by Takeda, whose alchymists were unable to recreate Zac's sentience, so he sent his henchmen to find his creation and the couple of alchymists whom fled from him.
Takeda's henchmen eventually found the couple's home and attacked them, ending up killing them despite Takeda ordering them to be taken alive. At the time Zac was casually exploring until he sensed his parents' distress, so he travelled through the pipes of the city as fast as he could, but he found that his parents had already been killed. In a fit of rage and grief, Zac unleashed the true destructive potential of his gelatinous body, killing many of the henchmen but also causing collateral damage to nearby buildings in the process. When he had calmed down, he was overcome with remorse so he rebuilt the damages he caused before moving to live in Zaun's pipe network from then on. Taking in both the positive and negative emotions of the people and occasionally acting upon his urges, Zac became an urban legend in Zaun.
Zac is an amorphous green blob of Zaunite ooze which congeals largely in his hands, forearms, feet, torso, and head. He has a large underbite with his green jaw, yellow eyes, and tail of slime that extends from his head. He can inflate himself into a ball shape.
Zac has an innate ability to feel the emotions of others due to his properties, often feeling overwhelmed by too much positive or negative emotions. Due to his upbringing from his adoptive parents, Zac has a kind, optimistic outlook of life and enjoys helping others, though when there are negative emotions around him he stops to intervene at best and lashes out in destructive tantrums at worst. He was overcome by rage towards his parents' deaths in the hands of Saito Takeda's men, yet felt remorse for the destruction he caused during his outburst, rebuilding everything he's damaged before choosing to live in the sewers alone. He feels a strong aversion to violence around him, yet usually remains in a calm demeanor when he fights.
- Ooze Composed Body: Zac is composed of a strange green Ooze that reacts to the emotions of other. This ooze was experimented upon until it developed sapience and became Zac. Because of this, Zac posses several strange abilities.
- Morphing: Zac can change his shape to whatever he wants with ease, solidifying and liquefying his body at will, and also compressing and decompressing into different sizes and shapes. He can enter small fissures and sewer pipes, and expand and involve others at will.
- Invulnerability: Thanks to his body, Zac is incredibly hard to injure. He doesn't have internal organs to protect and is impervious to most attacks, making him almost unstoppable in a fight.
- Superhuman Strength: By gathering enough of his mass in a solid form, Zac can wield great strength. This mainly involves him taking a humanoid form and using fists to cause devastating blows to his foes.
- Separation: Zac can separate his body in separate pieces, and then later reabsorb them.
- Empathy: Zac can feel and react to the emotions of others. This sometimes run the risk of causing him to become unstable and lash out in anger.
- Zac was born from a chem spill in Zaun's Sump level, gaining basic sentience to respond to outside stimuli. He was sequestered in a laboratory by a group of alchymists funded by chem-baron Saito Takeda, to be molded into a super soldier under his command. Two of the alchymists grew emotionally attached to Zac and, when they discovered who their benefactor was, spirited away with him deep within Zaun, lovingly raising him as their own son while being on the run from baron Takeda's thugs.
- Zac responds to people's emotions and acts accordingly, his mood changing with the reigning sentiment at any given time, best exemplified when he went berserk after his parents were killed by Takeda's men. After burying them, he decided to set off and help the people of Zaun, fighting chem-thugs and fixing the city's infrastructure when the opportunity presents itself.