What do you think a mare named Poison Apple would look like?

A dark red-and-black mane just like Princess Cadence, a yellow coat, and an apple for a cutie mark.

7635733
Ooh, I like the name. Sounds like a family member of Applejack's that turn gothic. I think a mare with at least some dark purple in her color scheme.

7635733
Well, if it was up to me, she would have an Arkansas black apple coat with a crimson and maybe a dark green mane. While the cutie mark is an Apple where one half is bright red, while the other is a dark purple.

Ooh, I'd probably go for a palette similar to this (I recommend the Coolors website, it's very fun):

7635733 Well the whole point of the poisoned apple in the fairy-tales was that it was deceptive, like a trojan horse. It wouldn't be obvious.

Most depictions of poisoned apples are of a bright red apple, usually very highly saturated, but that doesn't *really* fit with the more pastel palette of MLP. I suspect a coat colour similar to Big Mac's would work well though for that purpose; maybe lighten it a tad, but I wouldn't darken or saturate it further. As for the mane, well, green would probably work okay I think. Specifically a fairly pale shade; wouldn't want it to clash with the soft red coat. I could kind of see a maroonish purple work okay as well. Both green and purple are often associated with poison, but I personally think green works better since it's also a natural colour and would 'disguise' the meaning a bit better.

I could see purple eyes being a good choice. Again, purple is a bit of a corrosive and unnatural colour; it's rare to see in nature. Since the eyes are often considered a window into the soul, I think purple works best. In this instance a very violet shade would be good, and you could get away with saturating it a fair bit. For a really cool look you could use a green/purple gradient.

The cutie mark could go a number of ways. I quite like the idea of a red apple with bright pale specks on it; borrowing an aesthetic from the amanita muscaria, a famous and distinctive poisonous mushroom. A fun alternative that I really like is actually a cocktail with an apple slice in it; alcohol is a poison, and the idea of a more party-minded Apple is a bit of a fun twist on the 'poison apple' concept. Different vibe, though.