A [name_m]Court[/name_m] of [name_m]Thorn[/name_m] and Roses themed… How usable would you say these names are?
Girls:
[name_f]Feyre[/name_f] (fay-ruh)
[name_f]Amarantha[/name_f]
[name_f]Morrigan[/name_f]
Amren
Boys:
[name_m]Azriel[/name_m]
Rhysand (rees-and)
Tamlin
Thank you 
I’m barely familiar with ACOTAR, so this is from an outsider’s POV!
[name_f]Feyre[/name_f] - It sounds beautiful, but I think you’d struggle with the pronunciation. If I’m not wrong this is the protagonist’s name? I think it may be too tied to the character, personally.
[name_f]Amarantha[/name_f] - Lovely!! Like a more elaborate [name_f]Amara[/name_f]. She’s definitely rather dramatic, but not unusable, especially with her cute nicknames.
[name_f]Morrigan[/name_f] - I know a [name_f]Morrigan[/name_f] and she wears it very well !! It feels very modern, with a cool unisex vibe.
Amren - I’d assume this was a boys’ name based on how it sounds, and I think I do like the sound more for a boy, but it could definitely work on a girl too! Again though, I can only trace the name back to the books with no other history of use, but please correct me if I’m wrong about this! For me that makes it unusable, since I wouldn’t want to be directly, obviously named after a single fictional character with no other associations.
[name_m]Azriel[/name_m] - Definitely very cool, I love the old-sounding -riel ending with the cool Az- beginning! I’d probably assume an [name_m]Azriel[/name_m] came from a very religious family, just something to keep in mind.
Rhysand - Not a fan, sorry! Again, too strongly tied to an individual character for me, and I’d also pronounced it like “rye sand” if I didn’t have the pronunciation written down.
Tamlin - Really cute, but this one reads very feminine to me because of names like [name_f]Tamsin[/name_f], [name_f]Tammy[/name_f], [name_f]Tamara[/name_f], etc!
[name_f]Feyre[/name_f] (fay-ruh) → sound wise/vibe wise it works (like [name_f]Freya[/name_f], [name_f]Farrah[/name_f], Fay) but I do look at it and want to say it as ‘fair’ (as in, a village fayre) or potentially Fay-uh (like the end of [name_m]Dacre[/name_m] or Acre). I think it could work though
[name_f]Amarantha[/name_f] → bold and powerful, but sounds familiar enough and feels usable - kind of like [name_f]Amanda[/name_f], [name_f]Anthea[/name_f], [name_f]Athena[/name_f], [name_f]Dorothea[/name_f], [name_f]Amara[/name_f] etc
[name_f]Morrigan[/name_f] → mystical and cool, and easy to say and spell (for me - might not be for all?) I really like this one.
Amren → distinctive and interesting - I think it could work
[name_m]Azriel[/name_m] → literary and cool - fits in with other boys names atm
Rhysand - could be mispronounced (ry-sand) but I guessed it right since it has [name_m]Rhys[/name_m] in it. I enjoy it
Tamlin → it’s got a cool surname-y vibe - I like it and think it’s usuable
I think the thing with these is that none of them feel too tied to one series?
[name_f]Love[/name_f], love, love the ACOTAR books, so I might be a little biased 
I’d say all of these names are usable in the middle spot, so I’ll just focus on them as firsts.
[name_f]Feyre[/name_f] - I think [name_f]Feyre[/name_f] has a pleasant sound, but it’s quite likely to be mispronounced. It does look phonetic, but people almost always struggle on the first try. I know people who have read the books and still say it wrong, which sucks a little! I’d say it’s really only usable in the middle spot for the pronunciation reason, as well as the fact that it’s very tied to the series.
[name_f]Amarantha[/name_f] - I think [name_f]Amarantha[/name_f] is usable (a little less so than Amaranth), but it’s not one I’d ever personally use because of the character that [name_f]Amarantha[/name_f] is in the books.
[name_f]Morrigan[/name_f] - I’d say [name_f]Morrigan[/name_f] is also brave but usable. I can see problems with her getting confused as [name_f]Morgan[/name_f], but that’s only when said aloud.
Amren - Amren feels like the most useable girls name from the four you have here. I think it’s easy to say, looks nice, and has a pleasant sound.
[name_m]Azriel[/name_m] - I debate all the time if he’s usable (he is on my list though), and I think he is. The only thing that puts me off a little is the whole angel of death aspect, and how religious people might presume his parents as being, but those are just more personal. I would say [name_m]Azriel[/name_m] is usable.
Rhysand - I also go back and forth with Rhysand. I think there would be some pronunciation issues (a lot of people seem to say rye-sand as in rye bread), but I do ultimately think he’s usable, albeit very tied to the books.
Tamlin - Tamlin seems like it would be usable (for some reason more so in other countries than the US to me), but I feel like it also has a really strong tie to the book, and in this case I wouldn’t say that is super desirable.
Ranking them by their usability I’d say Amren, [name_f]Amarantha[/name_f], [name_m]Azriel[/name_m], [name_f]Morrigan[/name_f], Rhysand, Tamlin, and [name_f]Feyre[/name_f].
[name_f]Feyre[/name_f]— I think its usable albeit very tied to the series. I would see it as a version of [name_f]Arwen[/name_f] or Ėowyn. It has a very fantasy/fairytale vibe, but anyone who knows the series will assume that’s where you got it from. It is a beautiful name though, and I’ve has it and spelling variations on and off my list for years. As someone else already said, it feels like a new take on [name_f]Freya[/name_f] or [name_f]Farah[/name_f].
[name_f]Amarantha[/name_f] — I always thought this could be the new, cool version of [name_f]Samantha[/name_f]. The book character isn’t great, but I don’t think the name is the tied to it in the same way as [name_f]Feyre[/name_f] since she’s only in one book.
[name_f]Morrigan[/name_f] — great name, and I think it could definitely work. It is the name of a Celtic [name_f]Goddess[/name_f] so no strong ties to just ACoTaR, and is very intuitive to pronounce. It’s similarities to [name_f]Morgan[/name_f] also help make it more accessible for the current day imo.
Amren — I have an early 20s cousin named Amrynn, so I was already familiar with the name prior to the series. So, of course I think its usable. I see it as a very androgynous name too, so could work for anyone and I wouldn’t make assumptions. It is also the name of a character in the Witcher series too, so I wouldn’t see it as just tied to ACoTaR either.
[name_m]Azriel[/name_m] — a very cool choice, but it is a name that is a sensitive subject for a lot of Jewish and Islamic people. It’s the name of the angel of death in their religions and relating cultures so basically their version of [name_m]Lucifer[/name_m] and seen as a bad omen. I do think it is fairly usable though, and fits a lot of current trends.
Rhysand — I see this as very tied to the series as it was made up by the author. I also have always sayd Rye-Sand, as Ree-Sand is fairly unintuitive imo even with nickname [name_m]Rhys[/name_m] (rees). It also sounds like saying “Reese and”, as in someone names [name_f]Reese[/name_f] followed by “and”. Could be very confusing to anyone not seeing written down and extremely tied to the series as, unlike other names, it has no history beyond the series.
Tamlin — I still just think of the [name_m]Ballad[/name_m] of [name_m]Tam[/name_m] [name_f]Lin[/name_f], which was the inspiration of the ACoTaR character. The ACoTaR character isn’t a very positive one at present, however, so I don’t know if I would assume anyone naming their kid Tamlin was a fan, and rather, probably ignorant of SJM books. It does also read more feminine as a lot of modern [name_m]Tam[/name_m] names lean that direction (Tamsin, [name_f]Tamra[/name_f], [name_f]Tammy[/name_f], [name_f]Tamar[/name_f], Tameka).
So funny, I’ve been reading these books during my pregnancy and my ongoing struggles to name baby girl!
[name_f]Feyre[/name_f] really has my attention as I’m reading and I really love the sound and feel of the name. I’ve considered a few times it being a possible contender for baby girl in [name_f]April[/name_f], however, it’s not going to make the list! I’m not so much worried about pronunciation, the thing that stops me is that it’s a created name purely for these books and this character. As much as I’m fascinated by the name, I wouldn’t want to name my child for something so singular, a name created for a book that’s relatively new rather.
I’d love to see the name [name_f]Feyre[/name_f] take on a life if it’s own and one day reach the status of other names created for characters that now feel classic and well loved, (I believe [name_f]Wendy[/name_f] could be an example of this if I’m correct) but I’m not about to be the one to start that with [name_f]Feyre[/name_f]!
Rhysand nn [name_m]Rhys[/name_m], is a bit inaccessible if it weren’t for the nn, [name_m]Cassian[/name_m] I know a few already, know an [name_m]Azriel[/name_m] too. Tamlin I don’t care for.
[name_f]Morrigan[/name_f] is a name I love and would be considering actively if a close cousin didn’t have a [name_f]Morgan[/name_f] already!
[name_f]Amarantha[/name_f] is beautiful, dark and just a bit too much. Amren feels incomplete.
[name_m]Just[/name_m] for some context, [name_f]Feyre[/name_f], or [name_f]Fayre[/name_f], is a name that exsisted before this series. It’s the Old [name_m]French[/name_m] word for fair and has some history as a surname and given name. I’m not sure where Nameberry got it’s information, but SJM talked about finding it on a list on a now obsolete baby name site (20000 baby names I think, I believe she said it’s also how she came across [name_f]Elain[/name_f] and [name_f]Nesta[/name_f] too). Here is a link to more information behind it. I do think the name is rather tied to the series though, but if anyone’s issue is it not being a real name outside of this book series I don’t want that to hold them back! 
Interesting!!! Thank you!
I usually rely on BehindTheName for information regarding names and it had similar information to Nameberry and only “User Submitted” entries which tend to be less reliable than their curated entries! But it’s good to be reminded that no single resource will have all the information when it comes to a name, naming history is such a vast and complex thing!!