Compare and Analysis of the collection of the color in different season:
 Brand of Marc by Marc Jacobs is more using the brightness color in High Chroma co-ordinate with Black, Grey, Dark Blue or Dk. Brown in different season. Because the target customer is the young age group between 18 to 30 ages, and the price is lower than the Brand of Marc Jacobs, so Marc Jacobs' design is more trendy and youngful than the Brand of Marc Jacobs. And he is usually using the Adjacent Complementary Color Scheme and Principle of Novelty to present his collection in each season. A new or unexpected combination will draw our attention to his new collection in every season.
In another way, the color of the Brand of Marc Jacobs is more safely in using color in Black and Grey, Dk Brown in the collection. He is usually using the Scheme of Principle of Familiarity and Archomatic Scheme. But now he add some brightness color in High Chroma for a part of design in recent collection. 
In conclusion, I discover that many season he loves to using the Blue color in different Chroma or different Value in his collection to co-ordinate some new color(High Chroma in color) for autumn/winter collection. 
By the analysical in different way in PART TWO. 
Marc by Marc Jacobs--
Target Customer : Ladies' and Men's in Young Age between 20 to 30 age group who is trendy and stylish. (easy accept the trendy color for a change)
Price : Lower-Priced Line of Marc by Marc Jacobs compare to the Line of Marc Jacobs and the Brand of Louis Vitton. The second Line of Marc Jacobs. (More colorful difference to brand of Marc Jacobs)
The Look : Bright colors, oversize prints and graphic, layered looks, empire line, rugby stripes. (Shown on the Analysis of Marc of Marc Jacobs)
Marc Jacobs himself: Sexual Libertarian
Accessories : Mainly in Black and White, and adding the bright color in High Chroma(Trendy Color) for the Seasonal Fashion to Mix and Match.
Advertising : Have not choosen the beautiful Model. Mainly present the Mood.
For example that Model (Mr.)Cole Mohr dress up 2008 Autumn/Winter ladies' new collection. Natural Color background in Archomatic.
Black color is the main color in the advertising presentation, co-ordinate with Blue, Green, Red-Violet seasonal garments to emphasis the color trend of the collection.
Same concept as Marc Jacobs' dress up(men dress up skirt).
Interior and shop display:
Outside and inside the shop mainly in Black and White color (Cool Color Temperature).Using the Silver and Glass materials matching the white wall and Dk. Blue floor. To let customer feel more space, large, modern, clean and comfortable, free to walk in for shopping. 
It's easy to present the color in group by stories in each new collection.
Because shops are mainly in Black & White. Marc Jacobs usually like to adding some Colorful Trendy Color in High Chroma for the New Collection to attract the Young Mens and Ladies.
So, Window display usually present by the New Collection in High Chroma. (Usually using the Complementary Color Scheme) 
In another way........
Political & Economic: Unstable, many civil loss the job and the economic change to worse, they want to change and accept, support Obama to be a president.
Culture : Blue/Red/White(Flag), represent their Nation, Blue represent Stable, fresh and living life is changing. (My command)
(Obama may also affect the Fashion Color Trend for the America Designer)
Finally, Research from the Fashion Trend Book. There are many different way of color trend to develop the Fashion Color for the Autumn/Winter 2009/10 Collection.
We discover that Black/Grey/Redish-Brown/Beige are the basic color coordinate with Rose-Red/Blue-Violet/Yellow-Green/Green/Burgundy, etc.
This information use for the analysical Color of Marc by Marc Jacobs Collection(Autumn/Winter 2009/10)
In Conclusion that I predict the color of Dk. Blue(Keep on)/Reddish-Brown/Red-Violet/Yellow-Orange (Adjacent Complementary Color Scheme) for one stories of the New Collection of Marc by Marc Jacobs Autumn/Winter 2009/10.