@caitsith if you want a
really early example of contrast between Marcille and other elves, theres a dream scape where her mother briefly appears in chapter 3 page 2. Her mother's ears and especially eyes look more angular (a trait she doesn't share and is consistent in other elves).
I feel like with the way the author wrote the story, with the dungeon's true nature was slowly unravelled as the cast travelled deeper, its not possible to find a
concise obvious piece of foreshadowing. From what i can see the way they foreshadow is by leaving small visual or subtextual hints, non of which are 'neon' sighs of whats to come even on a reread.
There's pieces like the rabbits (ch1p17 -> ch64), the mention of liaus's great dog impression (ch17p22 -> ch40p16) which end up coming back tens of chapters later. Whether it's reincorporated details or whether it a 'Chekovs gun' style foreshadow is hard to distinguish but considering the consistency at which they do things like this its hard to believe some of this *wasn't planned* ahead especially when it comes to major story details, such as:
- The constant reference at the dungeon's degradation (ch6p4; ch9p5). As the world-building expands we learn tidbits of when the dungeon was discovered and how the culture around it has developed. It's then we get a scene where Kabru lays down bluntly where this is all going towards i.e. surface world destruction (ch32p25).
- The winged lion imagery, it can be considered a fun visual motif initially but once we discover of the more demonic origin of the dungeon this is re-contextualised. Especially when the demonic imaginary was hinted at a lot earlier (ch31p8 -> horned lion statue; demon reveal -> ch62).
- Marcille, her race and her ambitions could all be considered significant plot points considering how they are all relevant to the current story. She wants to equal life for all races because she doesn't want the people she loves to die. But what was the impetus for this? Chapter 42 lays out death via old age is her greatest fear, something she experienced with "papa" and her parrot, presumably at a young age. How would her father die of old age so young if he was also an elf? Her mother tells her that she "ran at different paces as everyone else". All this seems to heavily imply some non-elf parentage. (Also, earlier in ch39 the subject of life extending magic is brought up and Marcille indicates she's looked into it by commenting on the impossibility of it).
- The author herself has stated that characters such as Ituzumi have been planned since before publication (ch64.1p18). Thus its not a stretch that Marcelline, a main character, was also well planned before hand.
- The author has put a lot of emphasis on the subject of race throughout the series. Its a staple of character interactions, from jokes regarding difficulties identifying ages (ch13p28), to comments on the unequal treatment of certain races (ch33p10) or stereotypes and prejudices (ch20p2; ch56p13),
to gags regarding others misidentifying each other's race (ch39p9).
This last point is especially important because there never was a direct statement of fact by Marcille that she was a full blown elf. It's always been other characters which have called her one (ch8p16; ch9; ch15p5; ch20p2; ch28p10; ch30p4; ch33p3; ch36p9; ch56p13; ch57p4) and this has been consistently brought up. Marcille is consistently singled out as an elf (seemingly a lot more frequently than her party members) whether its a mention at how rare it is to see elves in a dungeon party, to contrasting her personality to that of a normal elves and their aloof personality, to the difficult history her presumed race has on the island.
Identification of race is also heavily visually based (as seen when the orc simply calls Marcille 'long ears' ch33 and humans are basically called 'tallman' in this world). This means its not infallible and in fact, and people have gotten it wrong: e.g. ch33p6 (played for a joke but still). As a possibly interesting note, the orc who calls Marcille a 'long-ears' (ch33) distinguishes Thistle as an elf despite both of them presumably being 'elves'.
When the whole race-bending scenario occurred, Marcille's races were always the most confusing to identify for Liaus. It was always marked with a "?" (ch50p5; ch55p26). This wasn't the case for other members of the party. As a half-elf it makes sense for a race change to make identifying the new race more confusing.
TLDR: The author's M-O with foreshadowing seems to be about starting small and simple before ramping up and they clearly stated having planned some things before even publication. While there's no glaring obvious piece of evidence Marcille was a half-elf in chapter 1, I think there is enough evidence that the author can and has planned things quite early in the publication (as evident by how structurally sound and flowing the main story elements are across the series) to support the idea Marcille's race wasn't made to be a half-elf part way through the series' publication.
