"A mad doctor, disgraced by Mann Co., is convinced he can take over the entire universe (and beyond) by turning himself into a human catfish! Unfortunately, he makes an enemy out of both the Red Team (particularly Scout and Spy), as well as Jon Taliban when he decides to send hordes of killer catfish, as well as kidnap several girls. Miss Pauling and Felicia included..."
- Adaptation Inspiration: While this story takes some beats from Blood Waters of Dr. Z, such as Dr. Leopold turning himself into a catfish and wanting to get revenge on those that wronged him and then mutating a woman to mate with and then eventually Take Over the World. But it goes in a completely different direction since he now has ties with MannCo. and later gets a few Dark Stalkers involved with his scheme.
- A Day in the Limelight: For The Scout, The Spy, and the returning Jon Taliban in this episode.
- Alas, Poor Villain: Discussed between Scout and Spy and then defied. After Dr. Leopold makes one last speech about wanting to swim in the ocean, Scout asks if they're supposed to feel sorry for him now. Spy tells him "Never. Professional conduct."
- An Arm and a Leg: When the Blu Scout tries double jumping over the mutated catfish infested waters in 2fort to the bridge, he manages to grab the ledge, but a few catfish manages to bite into his legs, biting them off. This causes him to let go of his grip and fall into the waters, where he's devoured.
- Apologetic Attacker: When Scout and Jon are forced to hit the mutated Miss Pauling and Felecia, Scout and Jon apologize as they land their hits on them.
- Big Damn Heroes: Chapter 3 ends with several members of the Red team saving Jon from the corrupting gangbang he gets from the mutated catfish.
- Bond One-Liner: Scout discusses with Spy and Jon about which one-liner he should use when they bag Dr. Leopold, but Jon just tells him to shut up.
- Break Them by Talking: Spy's plan on taking down Dr. Leopold is to have Scout use his obnoxious personality to deliver blows to Leopold's ego, which Scout does by making several bad fish jokes at him.
- The Bus Came Back: The Heavy, the Engineer, The Soldier, Jon Taliban, Felicia, Morrigan, and Rikuo all return from previous Arenas.
- Butt-Monkey: The Blu Team, who in the story gets massacred by Dr. Leopold's mutated catfish, gets their souls sold to Morrigan by Red Team in exchange for her help, and loses the match at the end of the story when they retreat into their Intel Room and make Among Us jokes about Blu Spy's outfit.
- Call-Back: Scout turning to Spy for help on dating advice with Miss Pauling, with Spy even brings up how the last time Scout asked for his help it didn't work out.
- Chekhov's Gunman: In the first chapter, Scout asks Spy about his pictures of a green-haired succubus he found laying around, he changes the subject to Scout's potential date with Miss Pauling. When Scout leaves, he takes a photo and remembers their competition they have fondly. In the fourth chapter, Spy summons the succubus, Morrigan, to help the mercs deal with the Mutated Catfish.
- Chest Burster: While the Sniper is having a Sniper Duel with the enemy Sniper, the Blu Soldier tackles the Blu Sniper in pain before several mutated catfish bursts out of Blu Soldier's chest and pounces on Blu Sniper.
- Continuity Nod: When Morrigan shows up to help Red Team, Soldier assumes Merasmus sent her and tells him to stop sending call-girls to him since he's taken.
- Damsel in Distress: Dr. Leopold kidnaps Miss Pauling and Felicia in chapter 3, with the intention of turning them into other mutated catfish and mating with them.
- Devoured by the Horde: Several members of the Blu Team get overwhelmed by the Mutated Catfish swarm and get eaten by them.
- Eye Scream: After Scout leaves his conversation with Spy, he considers giving his locker more traps, like a camera that blasts people's eyeballs out if they fail the facial recognition.
- When the Blu Demoman is in the process of getting eaten by the mutated catfish, one of his bottles explodes, revealing another catfish, who attacks his good eye.
- The Spy manages to sneak up on the empowered Dr. Leopold and stab him in one of his eyes with his knife.
- Face–Monster Turn: When Miss Pauling and Felicia are transformed by Dr. Leopold's formula, it makes their minds act more primal and gives them a desire to seek prey. This leads to them attacking Scout, Spy, and Jon when they enter Dr. Leopold's lair to stop his scheme.
- Forced Transformation: Miss Pauling and Felicia get injected with Dr. Leopold’s formula and turn into mutated catfish monsters like him, though they have other features from other fish.
- Friendly Rivalry: Spy and Morrigan have a friendly competition going over who can seduce more people, with Spy currently beating her.
- Groin Attack: The Sniper attempted to lop off Jon’s member when the mercs found him unconscious at one point.
- Half the Man He Used to Be: While Miss Pauling is cleaning up the mutated catfish infestation at 2fort, she comes across Blu Spy’s upper half trying to crawl away.
- Hand-or-Object Underwear: Scout puts some seashells on Miss Pauling to cover up her nudity after she is cured.
- "I Know You're in There Somewhere" Fight: When Jon is fighting the mutated Felicia, he tries to tell her to come back to her senses, but this doesn't work.
- Improbable Antidote: The cure for the mutations that Dr. Leopold gave to Miss Pauling and Felicia turns out to be Scout's Bonk! energy drink.
- Interrupted Intimacy: The mutated catfishes' gangbang with Jon ends prematurely by several of the Red mercenaries killing the mutated catfishes.
- Kill It with Fire: Jon defeats Dr. Leopold by using his Dragon Cannon attack on him, which blows up Leopold's lab and mortally wounds him.
- Late to the Action: After Dr. Leopold dies, the portal to Jon's universe glows and Rikuo comes out of it, wanting to stop the heresy that Dr. Leopold committed. Only to realize that the story is already over, so he heads back.
- Misplaced Retribution: While Dr. Leopold wants revenge on Saxton Hale for rendering his beloved Catfish species extinct, he begins his revenge plan by killing the mercenaries first due to their association with him.
- Mook Horror Show: When the mutated catfish attack 2fort, the Blu Team gets massacred by them.
- Nice Job Breaking It, Hero: The reason this plot starts is because of Saxton Hale driving the endangered giant Catfish species into extinction, with Kurt Leopold wanting revenge over this.
- Noodle Incident: When Jon is trying to remember what happened last night, he comments that he swears that he didn’t put his crotch into the sewing machine again.
- Not Me This Time: Before Medic offers an explanation for the sudden mutated catfish invasion, he clarifies that he didn't do another experiment behind everyone's back that caused this catastrophe.
- Oh, Crap!: When the Sniper sees several mutated Catfish burst out of Blu Soldier’s chest and chew off Blu Sniper's face, Sniper lets out a "Holy DOOLEY!"
- Porn with Plot: A retelling of Blood Waters of Dr. Z, but with several sex scenes. But only those on the Dark Stalkers side get the explicit ones.
- Pre-Mortem One-Liner: After Scout makes several fish jokes at Dr. Leopold's expense, Jon makes one of his own before dealing the finishing blow on Leopold:
- Jon Taliban: "Do you know my favorite dish? It's SMOKED SALMON."
- Pyrrhic Victory: While the sudden mutated catfish outbreak did lead to Red Team's victory, both of the intels were destroyed in the chaos, making their victory ring hollow.
- Red Shirt: It's the Blu Team ironically enough who are horrifically eaten by the Mutated Catfish to show how big a threat they are to the Red Team, who only get their gear wrecked in comparison.
- The Scapegoat: When Medic says that the one behind the mutated catfish outbreak was Dr. Kurt Leopold, Soldier assumes this means that Merasmus is to blame for it. He also assumed Measmus sent Morrigan to try and seduce him.
- Screams Like a Little Girl: Scout lets out a girly scream when Spy surprises him by decloaking behind him.
- Sex God: Spy, who has a competition with the succubus Morrigan and is beating her, with a record of seducing 400 people in a month. And in the epilogue where Spy and Morrigan have an orgy with a LOT of different people, Spy only considers it a warm up.
- Sequel Hook: At the end of the story, we have Baby Bonnie Hood stalking Jon and Felicia and planning on killing them, and Dr. Leopold’s body washes up ashore on an island from a completely different universe, where a cyclops picks it up and throws it back into the ocean.
- Shout-Out: When Medic explains that in the past Dr. Leopold proposed an idea to the Mann Brothers about making a race of half-man, half-fish creatures, Medic comments that it made a lot more sense than that [[Video Game/Portal Mantis Men project Aperture formulated]].
- Morrigan admits that if she wasn’t so busy she would have made Spy a royal consort, much like Tony Stark.
- Verbal Backspace: When Medic is talking about his past with Dr. Leopold, he mentions the studies they focused on back at the academy:
- Medic: "We used to go to the academy together. But while I focused more on torture-I mean, medicine, he focused more on marine biology."
- "Where Are They Now?" Epilogue: The story ends with explaining what each important character of the story did after Dr. Leopold was defeated.
- Your Head A-Splode: While infiltrating the Blu Base, a Blu Pyro shambles towards him for help, only for a Mutated Catfish to burst out of his head.
- Zerg Rush: Dr. Leopold’s method of killing the Red and Blu teams is to send hordes of his mutated catfish at them.
