Please be brutal(ly honest)!

If you are worried that the names might be slightly cruel then I'd avoid most of your girls names.
Clara would be okay, but all of the others are unusual enough for her to have to spend the rest of her life spelling them for people or being teased. (you did want brutal right?)

I love Theodora & Persephone (and Balthazar!)

I love Stella. Gorgeous name and not too popular.

Clara is perfectly nice.

Theodora is a bit clunky to my ears, and not a fan of Darcey (bit American and made up sounding).

Never heard Eila or Cliona before.

I'll be honest - I find Persephone and Hero highly pretentious and try-hard.

Of your boys names, I like Theodore (Theo) and Joseph best, although none really to my taste. None of the boys names are worthy of teasing, though, if thats your worry.

tempsperdu I stand corrected then! Perhaps these things are geographical too. Anyway, I still love it

Theodora
Dorothea
Theodore

Beautiful names. I wanted to call my DD1 Dorothea but 17 years ago it didn't work. I'd use it now, like a shot.

For Max you could also have; Maxian or Maximus

No offence will be taken - honest opinions please. Having a hard time persuading DH to any of my suggestions as he thinks them all 'odd' and is worried about teasing. Would it be cruel to saddle a child with any of these?
Theodora - horsey and un feminine
Persephone - too try hard
Cliona - clit
Hero - a bit try hard
Elia - how do you pronounce it?
Darcey - a bit 'Amber', not keen
Clara - perfectly nice
Stella - gorgeous

Max - lovely but so popular
Aengus - I don't really like it, but love Gus
Theodore - pompous and wet
Ethan - very 'Joshua'
Luca - without Mediterranean heritage? No
Jeremiah - ooh, nice
Joseph - v dull

I think very few of your names are odd, just not to my taste.

EmilyGilmore you may well be right there - but just based on my teaching experience, there do seem to be more Claras coming through in nursery/Reception classes. Might just be a local trend though (I'm in London).

I've noticed that you seem to get patterns of names with a similar 'feel' becoming popular in turn - for example, after Emily and Amelia became mega-popular people began to switch to alternatives such as Amelie, and then once these too increased in popularity you started to get similar-sounding names such as Elodie coming through.

tempsperdu I disagree with you on Clara - how can it have "exploded in popularity" when it is 179 (yes, I checked) in the ONS baby names list. I know LOADS of babies and encounter newborns most days. I can't recall a single Clara. Amelias and Sophias you're right, but Clara no. I think it might be just a name that gets a lot of Mumsnet coverage, like Persephone

I know there's one in Dr Who, but the other Dr Who names were already really popular, Amelia and Rose for example.

Do some people not know the myth surrounding Persephone? I think of it as a nice, seasonal changing, tale. I don't think it's at all dreadful or a reason for not using the name.

One description:
So, each spring Persephone comes back with the flowers that pave her way, to tell the story of rebirth, hope and harmony. And each fall when she leaves again for the Underworld below, her mother mourns and winter comes, while she waits for her return. Yet, for Persephone there is no remorse. She looks forward to the time she spends as Hades' Queen and wife, and to guiding those who have lost their way to the next phase of their life.

Obadiah, that's better

I knew it didn't look right...used to love Balthazar as well

Wasn't Jeremiah a bull frog?

I know a Thea...she is a cutie

Ethan and Joseph are nice and I like Jeremiah (one of mine was nearly an obidiah...I've probably spelt that wrong)

Dear God, Cliona (or Cliodhna, which I prefer, and both of which are pronounced CLEE-unna) sounds nothing like 'clitoris' or 'cleaner'. It's a name I really like. In fact, all your list us nice, bar Darcey and Stella which have a slightly dated and flashy connotation for me.

Favourites Cliona, Aengus, Theodore/a, Clara.

OK, you did ask for honesty...

Theodora - no - sounds too precious, plus Robbie Williams called his daughter this, and I loathe the man! Like Dorothea though.
Persephone - really like it, and the nn Sephy, but suspect it might be a bit 'much', unless she'll be moving in particularly artsy or literary circles. Pronunciation/spelling issues abound.
Cliona - clitoris again, I'm afraid. Shame, as it's very pretty in theory. Love Clio.
Hero - I get the appeal (big fan of mythological names here), and I like the non-girly -o ending, but I'd worry she'd be facing a lifetime of justifying her name to others. ('No, it's NOT a boys' name, it's from the Greek myth...')
Eila - OK - not awful, but seems a little flimsy, and open to confusion with other similar names.
Darcey - not keen. I'm a teacher, and have come across too many stroppy and entitled Darcey/Darcie/D'Arcys in my time. Plus it rhymes with arsey.
Clara - quite like it, but its popularity has exploded recently - think it might date (the new Amelia/Sophia?)
Stella - I want to like it, but it comes across as a bit brassy and brash to me (perhaps because of the lager and Stella McCartney connections?). Much prefer Estella or Celeste (or Aster, which also means star)

Max - meh. Loads of them about.
Aengus - love Angus, but this spelling just looks odd imo.
Theodore - like it, and nn Theo.
Ethan - a bit plain, but I quite like it.
Luca - much prefer Luke. Luca is pretentious in a minor celeb sort of way.
Jeremiah - no - it's either American President or American Bible Belt loon to me.
Joseph - massively overdone imo, but it's a safe enough choice

Overall you have a couple of nice options in there, but none that personally stands out for me. Names are incredibly subjective, though, so in the end you need to take everyone's opinions with a pinch of salt!

Theodora - like
Persephone - wouldn't use due to myth
Cliona - I'm afraid I'm another one who thought clitoris! Maybe because I'm a human biology teacher and not Irish.
Hero - too many possible songs: All I need is a Hero, We don't need another Hero, etc
Eila - Haven't heard of it. Potential spelling issues - Ella, Isla. There is also a Welsh name Eira.
Darcey - not keen, feels like a surname, rhymes with arsy
Clara - not keen, but maybe because I am in Australia, and when said with an Australian accent is really not pretty
Stella - sounds harsh. If you want the 'stars' meaning, go for Estelle or Celeste.

Max - prefer as nn for Maxwell rather than Maximillian
Aengus - really like Angus, haven't seen this spelling but assume it is Irish
Theodore - really like
Ethan - meh
Luca - prefer Luke
Jeremiah - not sure. Keep hearing song 'Jeremiah was a bullfrog'.
Joseph - like

What's so wrong with Persephone?

Sephy is a more likely nickname than Percy because of how it is pronounced, imo.

Me either, Irish people would really think your child had ideas above their station in life!

Very true!

Persephone is possibly one of the most horrendous names I've ever heard. Do people really use it?

Cliona is a very normal though not altogether popular name in Ireland. Absolutely no resemblance to clitoris whatsoever.
Darcy is fine
Clara is beautiful
I can't remember the rest. Oh yeah Eila I like but can forsee lots of spelling problems and pronunciation problems.

I like Hero. I suggested it when I was pregnant, because I love the painting The Last Watch of Hero, but DP told me it was ridiculous and vetoed it.

Are Eila and Aengus Irish spellings of Isla and Angus? Because I think they're both lovely names, but you'd be forever correcting the spellings here.

Me either, Irish people would really think your child had ideas above their station in life!

'What about Mary' they'd say 'Mary is much nicer than Hero'.

I don't get the whole Cliona/clitoris thing at all, maybe they pronounce it differently in the UK?

I would pronounce it and spell it with the fada.

Still not mad about it though! And Darcey seems done to death lately.

Hero? Really? Just, no.

I can't imagine anyone in Ireland being called Hero

Girl
Theodora - I know one, gets shortened to Thea.
Persephone - will be shortened to Percy, which I like. Pain in the arse to keep having to explain how to spell or pronounce it though.
Cliona - sounds a bit like a car.
Hero - I like this but she will have silly boys singing "Let me be your hero baby" after that Julio Englasias song.
Eila - I have no idea how to pronounce this.
Darcey - this is okay.
Clara - I like this a lot.
Stella - I know a baby Stella and I like the name.

Boy
Max - I know loads, all Jewish. It is a nice name.
Aengus - How do I pronounce this? People will think it is Angus (which I do like)
Theodore - I like it, people will know how to spell and pronounce it.
Ethan - it's okay, I don't love it.
Luca - it's okay, a bit funny if you are not Italian.
Jeremiah - one of the major prophets in Judaism. Will you be upset if people call him Jeremy or Jezza?
Joseph - I know one, this is a nice name. How do you feel about Joe? Because that is the nickname he will have.