You have some wonderful names on your list, Blade! I'll bold my favourites.
Ambrose - I love this name but Antoine and Ambrose share an initial (AN and AM)
Blaise - I really love this name with Antoine.
Cyprian - I like this name but I don't like the similar "an" between ANtoine and CypriAN.
Elias - This Greek version is lovely and I don't mind it with Antoine. Isn't the French Elie?
Evander - ANtoine and EvANder bother me. Unfortunatley, this name makes me think of the boxer more than the saint or mythology.
Laurence - A great classic name that so unappreciated. It deserves more respect than it gets. I'm biased because one of my favourite actors was Sir Laurence Olivier and I always think of blond actor Peter O'Toole on a camel in the desert playing "Lawrence of Arabia".
Leander - ANtoine and LeANder is not ideal.
Lionel- A vintage and underused choice.
Lucian - Oh how I love this name but again there is ANtoine and LuciAN.
Marius - This name is popular in Northern Europe. I like it!
Raoul - This has the same suave French flair as Antoine's so it's a great choice!
Victor - A great classic name which also has a wonderful meaning.
Raoul is such a cool name. I still really love Lionel for you too. And I think Ignatius is too good not to use. So my favorites are Raoul Ignatius or Lionel Ignatius. Either one sounds like it could be a brother to Antoine Raphael. I think that they are names that are unique, without being over the top or difficult to pronounce/spell. People will be familiar with them- even if they don't hear them a lot.
I like Lucien too, but I prefer Lucius.
Blade, where have I been! Congratulations, you dear beautiful creature! I literally swoon over most of your choices. I hope it's not too late to be helpful, because I'm about to gush all over your list, haha.
Ambrose - I love this for you...soft, rich, and powerful. Antoine and Ambrose is a darling pair, but they do sound a bit like twinsies. Have you considered Ambrose in the middle? There is the Aurelius Ambrosius connection.
Blaise - Love the soft burr of this one on the tongue, and digging the connections to Blaise Pascal and the patron saint of wild animals. The lisping meaning is unfortunate, but the Urban Dictionary entries make it so worth it ;) Antoine and Blaise is a lovely softly masculine pairing.
Cyprian - Huge fan of Cyprian. He brings to mind maps and clipper ships, dashing sea captains and the like. Not sure why this name is so gallantly nautical for me, unless perhaps it's the similarity to Caspian (but even then, Caspian is more high fantasy and Cyprian is more gentleman privateer). Antoine and Cyprian is definitely a swoonworthy combo. Shivers of happiness!
Elias - Elias is a strong, vintage, Biblical choice. I think it is a beautiful name, but it is not my first choice with Antoine. It strikes me as more puritanical and less historically and culturally rich compared to some of your other options.
Evander - The usability of Evan and Alexander with ten times the charm. The lore on this one is fabulous too! Antoine and Evander make an adorable sibset, and I can just see a little Evander with Antoine's glorious red curls.
Laurence - of Arabia? Cute ;) Love the laurel tree connection and the cadence of this name, but I have a deathly fear of the probable nickname Larry! Antoine and Laurence are quite handsome together though!
Leander - For you, I like this even more than Evander! The Hero myth is beautiful, if quite tragic, and what little boy wouldn't want to be named "lion man"! Antoine and Leander is another swoonworthy combo, for sure.
Lionel - Another fabulous leonine choice, and the Arthurian knight is an excellent namesake. This one is thoroughly tied to the singer Lionel Richie for me, however, and I vastly prefer Leander. Antoine and Lionel do not pair well enough to sway that opinion :)
Lucian - Adore. I have mad crazy passionate love for Lucian and I always have. He's just so lush and dashing, and I love the juxtaposition of the "light" meaning with the often dark (or misunderstood?) characters who bear the name. But I digress. Antoine and Lucian is a sibset to die for!!!
Marius - A lovely choice, not one of my favorites. I do like the ancient feel, but the simialrity to the common Mario kills some of the magic for me. Antoine does dazzle him back up a bit though...Antoine and Marius is quite charming.
Raoul - I share the mad love for Raoul...I love the liquid-airy sound and feel and taste of it as it rolls off the tongue. Such a rich sensory name! The wolfish meaning appeals to me too, and it's one of the best matches with Antoine yet. Antoine and Raoul...Antoine and Raoul...Raoul and Antoine...Antoine Raphael and Raoul...I can't stop saying it!!
Victor - Not as melodic as some of your other choices, and can come off as a word name, a la Ransom and Chase, despite the long history of use and namesakes such as Hugo. Have you considered Vittorio? Antoine and Vittorio sounds much more harmonious to my ear than Antoine and Victor.
My favorite firsts are Cyprian, Lucian, and Raoul, though I love nearly all of them. Of your middles, Altair, Aurelian, Ignatius, Rainier, and Theodosius are my clear favorites, Theo and Nash being the wild cards. While I can see the appeal of Athanasius and Auxentius as unique and original choices after powerful historical figures. they are a little over the top even as middles. Antoine Raphael is magically delicious without being pretentious, and I think that is a good formula to follow for baby number two as well. I love the sound and feel of Esmond, and the meaning is beautiful. I just fear it would be mistaken for a lopped off Desmond.
Antoine Raphael and Lucian Rainier - I die. Simply. Die.
Antoine Raphael and Lucian Altair - so melodious! I love how the cadences are the same as well, it ties the sibset together
Antoine Raphael and Lucian Theodosius
Antoine Raphael and Lucian Aurelius - only because the two -ian endings back to back was redundant
Antoine Raphael and Lucian Ignatius - love the repeated "sh" sounds
Antoine Raphael and Cyprian Ignatius
Antoine Raphael and Cyprian Altair - This name just got even more "adventuring seafarer" for me with the addition of starry Altair. I didn't know that was possible!
Antoine Raphael and Cyprian Theodosius - a mouthful, yes, but a delectable one!
Antoine Raphael and Cyprian Aurelius - same reason for the suffix switch as with Lucian. This actually turns out to be quite dashing!
Antoine Raphael and Raoul Theodosius
Antoine Raphael and Raoul Altair - I didn't expect to enjoy this one because of the profusion of Rs and Ls and vowels...but it's really quite liquid and magical! I love the AR - RA initials as well
Antoine Raphael and Raoul Ignatius - utterly handsome
Antoine Raphael and Raoul Rainier - too much alliteration?
I feel that Cyprian Rainier and Raoul Aurelian have too many similar back-to-back sounds to make workable combos.
All this to say, my absolute very best favorites are....
Antoine Raphael and Lucian Rainier OR Antoine Raphael and Raoul Altair
Cannot wait to see what you choose, my dear!! After I've rested up a bit, I'll check out your girls' thread that I know has to be around here somewhere. Cheers!