Anticlimax Boss: Gobol. He's a Vinean genius in robotics and has a whole space city of Mecha-Mooks doing his bidding. He doesn't age thanks to the emissions of vinadium and can spam energy beams from his hands. Lyco simply blows up his energy diffuser, causing him to age rapidly and turn to dust.
Broken Base: Time Travel first being invented in 1934 as opposed to the 39th century as established in an earlier story. Some fans had a hard time believing it could be achieved with pre-WWII technology while others fans pointed out this was possible in other sci-fi works such as H.G Wells' The Time Machine.
Complete Monster: Karpan is a member of a Vinean colony on Earth. Driven by his hatred of Earthlings, he attempts several times to kill Yoko, Vic, and Pol, from the second they meet (The Curious Trio). Seemingly redeemed at the end of the book, he becomes worse in his next appearance, deliberately making sure an accident linked to the colony's activities would happen, which would lead to Martinique being wiped out and killing thousands, so that he can set up a base of operations before taking over the world. When Yoko and her friends attempt to stop him, Karpan cuts off the air from a chamber and vents toxic gas to kill them, even though it means killing his own workers in the same room (Vulcan's Forge). A threat even after his death, Karpan turns a young half-Vinean half-human hybrid into a Tyke Bomb with a pre-programmed mission to activate a program to end all life on Earth, allowing the Vineans to take over (Khany's Secret). Selfish, power-hungry and willing to harm both Earthlings and Vineans, Karpan proves to be one of Yoko's nastiest foes.
Creator's Pet: Emilia seems to be taking that route, co-starring with Yoko since album 24. Leloup imagined her as a lead character for a new series set in the 30's. Realizing he couldn't commit to two series at the same time, Leloup introduced her in Yoko's universe.
Dry Docked Ship: Yoko and Vic. A rare in-canon example where the writer himself has chosen not to pursue Yoko's relationship because he felt it would upset the many fans who were "in love" with Yoko themselves. In a similar vein, none of Yoko's many friendships (almost exclusively with women) are given sexual overtones, in spite of the platonic love between characters.
Ensemble Dark Horse: The Vineans. To think they were initially meant to be one shot characters.
Fandom-Specific Plot: It's not uncommon for fans to write fanfictions about an adventure with the trio, the Vineans, Ingrid and Monya together as the two latter never met the Vineans in the series.
When Dr. Schulz put Magda in the pod to preserve her life, he was already making research on cell preservation. Since the incident happened in WWII and his home town Rothenburg was very pro-Nazi, was Schulz working for the Third Reich?
Professor Zimmer. Since that he mentioned working on Wotan's fire in the 30's, he could be a former Nazi scientist.
Hegora is the tyrannical queen of the abyssal city. Should anything happen to her, the city will cease to function and die. After Hegora is disposed, Yoko is made the queen so the city could endure. However, unlike Hegora, Yoko is not an android and doesn't have backup bodies. What will happen when Yoko passes away?
Harsher in Hindsight: In The Three Suns of Vinea, Khany returns to her home planet for the first time after 2.4 million years. She's optimistic about reuniting her people and restoring happiness to everyone. Fast forward to The Temple of Immortals, and we find that those who returned to Vinea require a long period of adaptation and many fail to survive. Things are desperate enough that The Vinean Council has considered invading the Earth and wiping out humans. This has led Khany to cut all ties with her home planet to protect Earth and themselves.
Les Yay: Yoko tends to pick up a lot of female friends, and tends to become very close with them.
Khany's Secret contains the most undertones of this, especially after The Reveal that there is an artificial human-vinean hybrid to which Khany gave cloned organs of her, and some brainwaves from Yoko, making her their spiritual daughter. Then there is the unfortunate wording of a commentary from the author explaining he did not show Khany and Yoko making up after being somewhat at odds during the story, because "they were going to reconcile in private, away from everyone."
Nightmare Fuel: At one point, the villain of the day pins Yoko's neck to a support beam with a screw clap.
Sequelitis: It's generally agreed that the first 15 issues or so are the best while the series afterward becomes stale and repetitive. The introduction of Emilia and the increasingly Off-Model artstyle exacerbate it further.
Strangled by the Red String: Pol and Mieke. There's little interaction between the two, and yet they both fall in love at the end of their adventure.
The Scrappy: Emilia MacKinley. Leloup said that fans wanted to strangle the life out of her the moment they laid eyes on her. This was due to a bad first impression Emilia made when she nearly rammed Yoko and refused to apologize. She mellowed her jerkass-ness later on, but the damage had been done. Some fans say she's not that bad and is similar to other obnoxious girls like Myrka or Litsy. Since as the stories go on, regulars like Vic, Pol, Morning Dew and Mieke have fewer appearances and Emilia takes on a larger role, there's no end to the debate.
Values Dissonance: Yoko's grandfather buying a Chinese servant in Hong Kong for her mother. Back in the late 19th century / early 20th century, this was generally accepted, but it is unthinkable today.
Villain Decay: Ito Kazuky is much less of a villain in "The Rhine Gold".
Win Back the Crowd: In "Khany's Secret", Khany has a more active role after having been relegated to a minor character in her last appearances. She's even on the cover along with Yoko. On the other hand, Emilia's role has been reduced.
