I think Holly is central to this mystery, but I think we are either misunderstanding her character or being misled about her. For that reason, I want to point out some discrepancies I've notice beyond her inconsistent eye color.
Firstly, the difference between the plants Holly and Mistletoe:
Holly
Family: Aquifoliaceae
Berry color: Most commonly red
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Mistletoe
Family: Santalaceae
Berry color: White
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Sometimes, Holly and Mistletoe are combined to form decorative mistletoe, as seen here: http://www.mistletoe.com/images/mistletoe-holly-sprig-new.jpg Note that the two plants are combined; they are not one in the same.
The reason I point this out is because both Mistletoe and Holly are themes within the comic, Holly being a character we know is "...hiding something", and Mistletoe being the Mistletoe lounge.
Details about Holly are inconsistent throughout the comic, from her eye color to the plant she adorns. To make this case, I first want to set out to prove that the comic's artists are aware of the difference between Mistletoe and Holly, including of their differing berry colors.
On page 5 of the comic, Holly is pictured next to a sprig of Holly (red berries): http://imgur.com/7R5pPE4
Also on page 5 of the comic, a business card for the Mistletoe Longue is pictured with a sprig of Mistletoe (white berries) printed on it: http://imgur.com/EpjzzQ0
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Knowing the comic's artists are aware of the differences between Mistletoe and Holly, I believe it can be concluded that deception of either plant is intentional, and that they are not meant to be taken as one-in-the-same.
Now take into consideration some evidence which suggests that the person purported to be Holly throughout the comic may not always truly be her. Two key points here will be her proximity to actual Holly sprigs and her eye color.
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Holly's eye color on trading card three, as a baseline for her true eye color: Blue
http://i.imgur.com/EPpMNIX.jpg
Chronological appearance of Holly throughout comic:
Page 4, eyes closed, pictured below sprig of actual Holly (red berries): http://cdn.akamai.steamstatic.com/steam/clusters/sale_winter2015_comic/397a5a0d/b11a634c_day_3_english.jpg?t=1451758311
Page 5, black&white, pictured near actual sprig of Holly (red berries): http://cdn.akamai.steamstatic.com/steam/clusters/sale_winter2015_comic/397a5a0d/d2085828_day_4_english.jpg?t=1451758311
Page 9, eyes closed, No Holly sprig nearby: http://cdn.akamai.steamstatic.com/steam/clusters/sale_winter2015_comic/397a5a0d/6912b084_day_8_english.jpg?t=1451758311
Page 11, eyes green, ***Wearing a sprig of MISTLETOE (white berries): http://cdn.akamai.steamstatic.com/steam/clusters/sale_winter2015_comic/397a5a0d/fdca62d7_day_10_english.jpg?t=1451758311
Page 12, black&white, neither wearing Mistletoe nor nearby to sprig of Holly: http://cdn.akamai.steamstatic.com/steam/clusters/sale_winter2015_comic/397a5a0d/88a2d829_day_11_english.jpg?t=1451758311
Page 13, black&white, neither wearing Mistletoe nor nearby to sprig of Holly: http://cdn.akamai.steamstatic.com/steam/clusters/sale_winter2015_comic/397a5a0d/fcbdfd41_day_12_english.jpg?t=1451758311
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Is Holly really who we think she is throughout the entire comic? What's with the interchanging use of Holly and Mistletoe when the artists clearly know the difference between the two? Why would Holly wear mistletoe instead of holly when she is so often associated with sprigs of holly early on? Am I losing my god damn mind?
