Is there a difference? Are they flat out the same? Is one a subtrope of the other?
Talk:Legal Jailbait
I believe Legal Jailbait is when a character looks like he/she is underage, but in the plot of the story, is confirmed to be older than legal age, possibly much older, and there is proof of this in-story. The scene in Buffy where Drusila (I believe) can't order alcohol in a bar despite being centuries over legal age is an example.
Totally Eighteen is when a character looks like he/she is underage, the plot or the script is insisting the character is legal age; no actual proof is given in-story. Often a meta example. For instance, in Aladdin (1992 Disney film) and Tangled Jasmine and Rapunzel clearly look like teenagers, but both are 18 according to the scripts.
Note that in both cases, if the actor is underage, the Trope is Dawson Casting
The way I read them:
- Totally Eighteen is like Have I Mentioned I Am Heterosexual Today?, in that they're both dialogue tropes - somebody keeps saying that this is the case.
- Legal Jailbait is a form of Author Appeal, where the appeal is toward somebody who looks young but is actually of age.
- Dawson Casting is when the actor is older than the character, not younger.
Totally Eighteen is that line on Ero Games/School themed hentai that say "Every character in this story is over eighteen years old/of legal consent age in the jurisdiction this game is published". Because these Japanese teenagers who in dialogue are in second year of what it seems high school are really truly 18, so you can watch them boinking without being arrested for child porn consumption, claro que sí, campeón.
Legal Jailbait is, exactly what Robkelk said, authors who like their Lust Interests underdeveloped, but because they don't want to be labelled as child pornographers they make the in story claim that the character is actually legal despite everything in their looks (and sometimes even their personality) saying otherwise.
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