Using mostly www.behindthename.com and genealogy.about.com/library/surnames/bl_
Ace of Diamonds - Yvette Moreau
Yvette - Derived from Germanic iv meaning "yew". This was the name of a 14th-century saint from France.
Moreau - From the Old French, meaning "little dark."
Yvette has a pretty and elegant sound to me, and Moreau evokes the fact that her family is darker skinned compared to some people in Lorena.
Ace of Clubs - Montague Orchard
Montague - From a surname meaning "pointed mountain" in French.
Orchard - An inclosure of fruit-trees. Orcheard, Gaelic, a goldsmith.
Montague is a slow and somber sounding name to me, befitting Montague's personality. Orchard sounds simple and has a nicely ironic value since he's never seen a forest.
Ace of Spades - Sibyl la Bornieta
Keep wanting to spell this as Boritainne. Boritain is apparently a possible old spelling of Britian.
Sibyl - From Greek Sibylla, meaning "prophetess, sibyl". In Greek legend the sibyls (who were named for Sibyl, the first of their kind) were ten female prophets who worshipped the god Apollo.
la Bornieta - 1520's ish French surname meaning 'one eyed'
Sibyl's a small secretive slip of a girl who reminds me of Makubex from Get Backers. I doubt this is her real name.
Ace of Hearts - Armand Corwin
Armand - French form of Herman, Means "army man", derived from the Germanic element heri "army" combined with man "man".
Corwin - (origin: Cor. Br. Local) The white castle; from caer, a castle, and win or gwin, white; or the white choir. Also evoking the Coer de Leon
Armand reminds me of Aziraphale from Good Omens. He's a good hearted patriotic man who's rather sappy about the national anthem and means well. Corwin's purely for the heart associations.
Queen of Spades - Dominique Sommers
Dominique - French feminine form of Dominic. From the Late Latin name Dominicus meaning "of the Lord". This name was traditionally given to a child born on Sunday. Several saints have borne this name, including the 13th-century founder of the Dominican order of friars.
Sommers - meaning is for Summer - So called, probably, from the season summer. The word is derived from the Saxon Sumer; Celtic or Gaelic, samh, the sun. Summer, one who casts up an account. The name may be a corruption of Sumner.
Dominique is a born leader. I wanted her name to have 'dom' in it, and to evoke a sort of - mastery of the world around her.
King of Hearts - Delano Leroy
Delano - Origin: Old French. Meaning: of the night.
Leroy - Meaning "the king," the French surname Leroy derives from the Old French "le roi."
First name is a horrible pun on the fact that he's the son of a 'lady of the night' if you wish to be diplomatic. Last name is fake, and purely chosen to evoke "le roi".
King of Spades - Alex Lupin
Alex - shortened form of Alexander - From the Greek name Alexandros, which meant "defending men" from Greek alexein "to defend, help" and aner "man" (genitive andros). Alexander the Great, King of Macedon, is the most famous bearer of this name. In the 4th century BC he built a huge empire out of Greece, Egypt, Persia, and parts of India. This was also the name of emperors of Russia, kings of Scotland and Yugoslavia, and eight popes.
Lupin - evoking the blue flowers of the same name, and Lupine
Alex is a doubled character both working in the law as a cop and out of the law as a Card. The androgyny of the name is deliberate.
Joker -Damien Montechristeu
Damien - French spelling of Damian. From the Greek name Damianos which was derived from Greek daman "to tame". Saint Damian was martyred with his twin brother Cosmo early in the 4th century. They are the patron saints of physicians. Another saint by this name was Saint Peter Damian, an 11th-century cardinal and theologian from Italy.
Montchristeu - fake. Mont = mountain Christeu - evokes Christ. Also evokes the Count of Monte Christo
Damien's probably one too many D names. I'm fond of the meanings of it. The last name is supposed to sound a bit stuffy.
Card Killer - Hector Gantelet
Hector - Derived from Greek echein meaning "to hold, to possess".
Gantelet - Old French gantelet, diminutive of gant, glove
Hector wants desperately to hold on to power in the government and to hold on to Yvette. Sadly, he has neither.
City name - Bona Lorena
Bona - evokes "good"
Lorena - From the Roman cognomen Laurentius, which meant "of Laurentum". Laurentum was a city in ancient Italy, its name probably deriving from Latin laurus "laurel". Saint Laurence was a 3rd-century deacon and martyr from Rome. According to tradition he was roasted alive on a gridiron because, when ordered to hand over the church's treasures, he presented the sick and poor.
Lorena sounds like something that could be a lovely place. The fire references is also amusing. I'd prefer something like Morgan for the water references, but it works. Bona means city in some language I've forgotten.