Butterfly Unicorns Sheet 1 [OPEN]

This is my first attempt to step into the world of adoptables. As a result, I'm willing to negotiate prices.

Also, this lineart is mine. If you have seen it somewhere else before, that's because I have used these lines for other purposes before.

My Rules
1. Once you have paid for/claimed an adoptable, it is yours to do with as you please. You can edit the design as you wish, and you may use it as a breedable and sell offspring.
1a. However, I would prefer these not be used as My Little Pony characters. I have nothing against the show, but I feel these don't really fit with its canon.
1b. If you want to edit the design, please draw the new design on another set of lines, instead of editing my art.
2. Please credit me at least the first time you draw your adoptable/put a picture of it in your own gallery.
3. You may resell your adoptable if you wish. However, I would prefer if you wait at least a month before doing so. You must also state its original price along with your own price.

Prices (The names are merely for identification, feel free to give them your own)
1. Chocolate Creme-5
2. Scarlet Harvest-10
3. Don't They Know It's Christmas-10
4. Mariposa Rainbow-15

Customs
There are 4 custom slots open for 15 each. There are also 2 free slots for people who are the first to answer the following questions:
1. Where have these lines been used before?
2. Rule 1a may seem ironic due to one of the adoptables' sale names. Which one is it, and why?