The difference between the first and second time facing "Siegfried" is that the first time, only Ramon stepped in to help Jacqueline, whereas the second time everyone did. After the first time, Jacqueline very quickly strikes out on her own and turns against her companions. Perhaps the whole thing was triggered by Jacqueline's fear, as she was about to die, that her companions wouldn't have her back, and it just got sort of twisted from there.
This exchange at the beginning of the episode:
"Siegfried": I am Siegfried. My sword is called Notung. Jacqueline: Your name and the name of your sword may be the same as the famous myth, but I doubt that your sword is invincible. "Siegfried": My sword is Notung. Jacqueline: I’ll give you “no tongue.”
At first, it comes across as an awkward way to force both exposition and a Pre Ass Kicking One Liner into the dialogue. When you consider the slightly confused look on "Siegfried"'s face, and the fact that he only thinks he's a legendary figure, it's easy to see the exchange as a case of Pre Ass Kicking One Liner as an in-universe Enforced Trope, where the Genre Savvy villain repeats a line that's supposed to prompt an obvious Incredibly Lame Pun until he gets the expected reaction out of his opponent.
112 "The Chameleon"
The Chameleon can look like anyone, including changing his body shape, skin tone, apparent gender, voice, and clothing — and yet he can't disguise the ink from Siroc's ink trap. This makes sense, however, if you realize that he simply didn't bother to disguise the ink because he didn't realize it was there. When the ink comes into play later, it's only from the heroes wrongfully assuming that not having ink on their hands will prove that they're not the impostor. The actual Chameleon is not shown with ink on his hands again once he realizes it's there. The heroes simply got lucky that the Chameleon revealed himself and they didn't have to rely on the ink stains to prove his identity.
Throughout the series, Siroc doesn't show much interest in women — not necessarily because of a lack of sexual desire, but because they're a distraction from his scientific work. So what's the only point in the show where he explicitly has sex? When he needs human test subjects for his newest experiment. (A bit of Fridge Horror there as well.)