Eye colour... actually, green is more feasible than you might think! Virtually all elves with defined eye colour have grey, of course. A handful have blue (notably, in one instance, Olwe king of Alqualonde), but it's pretty much grey throughout. The only green-eyed character I know of in the Legendarium is Gollum. ;)

But... what colour is that 'grey'? In several instances, it's sea-grey, and to my mind, that speaks more of a washed-out (ha ha) green than of pale blue. So you could definitely argue for a 'sea-green'-eyed elf, of any kindred. You'd have a hard time pushing for 'grass-green', though.

Hair colour is... heh. As Nesh said, the only red-haired house is that of Mahtan, and through his daughter some of House Feanor. But that's fine, we don't know where Mahtan got his colouration from, he could have relatives dotted around all over the place. But aside from that... hair colour among the Eldar seems to be metaphysically linked to their attributes. Mahtan the smith has fiery red hair; three of his grandchildren share it, of which two (Maedhros and Amrod) died in fire; in fact, their whole house has a fire link. Similarly, the 'holy' Vanyar are blonde, with that light-connection; Elu Thingol, the king of the starlight, has silver hair; Thranduil is a gold-crowned king. Etc etc etc. So, annoyingly, in Middle-earth, the cliche 'fiery redhead' might actually make sense.

Coming back to the eyes: I'd trust the Nandor about the sons of Dior, since they've got a long tradition of accurately transmitting spoken history. But I don't think it'd help. Beren had blue-grey eyes and somewhat fair hair (due to looking exactly like Tolkien), Luthien had black hair and grey eyes (of course); Beren descended from both House Beor and House Hador, but all known descriptions give them grey and blue eyes respectively, and dark and blond hair.

There just... aren't any green or brown eyes among the Quendi or the Edain. Everyone who reached Beleriand had grey or blue eyes, despite those both being recessive. For brown (and therefore 'grass-green' and related colours), you'd have to look at the races of Men who spread south from Hildorien rather than west, or who stayed put: the Varags of Khand, the Haradrim, the Easterlings and the like.

(There are two exceptions to my blanket statements above, and they're both hilarious:

1/ The Hobbits seem to have been of 'eastern' stock, making them browner than the Edain, and probably brown-eyed. Apparently they fled the East around the beginning of the Third Age - probably when Sauron's spirit fled from the Last Alliance in defeat and set up a long way to the east.

2/ The Druedain/Wild Men/Woses had, apparently, glowing red eyes. They're the only non-blue-grey race who reached Beleriand - oh, except for Ents, who had brown/gold eyes. I don't think that's helpful, though)

So, uh... are you trying to make a red/green OC (and if so, why?), or to justify one, or to denounce one? It's kind of hard to tell.

hS

PS: Darn, now I'm going to end up analysing why there are so many varieties of short people in Arda. Hobbits, Dwarves, Petty-dwarves, Druedain...

Yeah, probably as an elf would impossible, but there's a possible workaround, if the green eyes were to be considered a Edain-only characteristic; the OC could be Half-Elven, a faaaar descendant of Eluréd or Elurín, since no one knows what happened to the twins; but Nandor tradition sustains (according to the Quenta Silmarillion) that they survived "led to the safety of the woodlands by birds and beasts".

Yes, I'm aware of the implications, I don't like them much either, I will have to look for other ways to crush the Sue-ness before it gets worst.