Harlequin and magpie are both expressions of an option on the E gene, which determines how the dark color extends down the hairshaft, especially on the agouti hairshaft, which is usually formed with a dark tip, middle fawn/orange band, and a dark base color.
Most dominant is E(D), which makes the entire hairshaft dark. Next is steel E(S) which moves the middle yellowish band near the tip (gold tipped steel in a normal full-color C rabbit, alternatively, the chinchilla gene c(chd) removes all the yellow tones, leaving pearly white--the silver tipped steel.) Normal extension of the common rabbit colors is next, E. Now we finally get down to your harlequin/magpie question, it is next to the most recessive option on this gene. The only color more recessive to harlequin is called non-extension., the gene that causes the main body color to be yellow (orange/red/cream/fawn) tones instead of dark (blue, black, chocolate, lilac)--tortoise shell self colors and orange, red, fawn and cream agouti colors.
So, back to your harlequin--the harlequin e(j) gene causes the dark and yellowish bands to be in patches on the skin instead of bands on a single hairshaft. Rabbits with two copies of the harlequin gene, or a harlequin and non-extension gene, and the normal full-color C gene are some form of harlequin. They can either have very definite color bands, like the Harlequin breed, with a color split down the middle of the face, opposite ears, and opposite legs, and multiple color bands down the body; or just mixed light and dark hairs, called 'brindle', or anything in-between. The dark color can be black, chocolate, blue or lilac. Blue or lilac harlie rabbits will have paler yellow patches than the black or chocolate varieties. Rufus modifiers are a separate genetic that can tint the yellowish patches orange/red.
Magpie is the same e(j) gene, only this time it is paired with the chinchilla c(chd) or sable c(chl) gene, which removes the yellow tones from the hair, so the dark colors are alternated with a creamy white shade instead of fawn/orange.
Chocolate magpie is usually an agouti (A__), chocolate bb on the black/brown gene, Full color on the C gene, dense color D_ on the dilute/dense gene, and e(j)_ on the extension E gene. Lilac magpie would be usually an agouti (A_), bb chocolate, change the full color C to chinchilla c(chd), and the dilute dd on the dilute/dense D gene; both have the same e(j)_ harlequin gene. Just as an aside, adding the dominant broken En en gene makes either of this rabbits into a tricolor, just a fancy name for broken harlequin. It can be hard to see broken on a magpie, as it is white spots on a partially white rabbit.
As to the Vienna question--Vienna blue-eyed white is a recessive gene, coded vv. Normal coloration is non-vienna VV. The Vienna carrier (VC) or Vienna-marked (with varying amounts of Dutch-like white on the toes, stripe down the face and collar) rabbits are Vv. Mating two VM or VC rabbits will give the expected average results to be half Vv carriers, 1/4 normal non-Vienna VV, and 1/4 Vienna blue-eyed-white vv.
