Harmonia
Harmonia Blood Code Study- Eva Roux "A blood code received from Eva. It holds her will to pay back and dedicate her life to the one who saved her from being a slave. This code improves focus bonuses and features excellent Dark Gifts. It is weak to being staggered but supplies ample amounts of ichor."
Introduction to Blood Codes and Eva
Blood Codes are the abilities imbued within a Revenant's Blood. Each Blood Code is unique to each Revenant that resides within the Gaol of the Mist. Once a Revenant has awakened from their slumber after the BOR parasite has been placed in them, the blood takes on a Code which I believe derives from the characteristics of that Revenant.
Eva willingly became a Third Generation Revenant during her time with Jack. She is completely devoted to Jack and is willing to do anything to assist Jack or take on burdens that would cause him less pain. Even when her strength falters or she's at the edge of a frenzy, she'll prioritize Jack's wellbeing. Jack has the same feelings when it comes to protecting Eva as well. That's why these two balance each other so well as Watchers of the Successors.
Greek Mythology
Eva's Blood Code is based on the Greek Goddess Harmonia.
Harmonia was known as the Goddess of harmony and concord. The only notable story linked with this Goddess is the Necklace of Harmonia. It all started with Hephaestus, who discovered that his wife Aphrodite the Goddess of love had cheated on him with Ares the God of War. He cursed their future bloodline saying that any offspring from them would be cursed. Harmonia is Aphrodite's daughter and Harmonia was to be wed to Cadmus, the founder of the city of Thebes. When Hephaestus heard about the marriage, he created a necklace for Harmonia and offered it as a gift.
The Necklace of Harmonia is said to bring misfortune to anyone who their possessor is. In exchange, the necklace grants eternal youth and beauty to the one who wears it. The necklace itself was made from gold and jewels and it had two small snakes clasped on the gem
Due to the exploits of Cadmus, when he was ready to sacrifice a cow to the Goddess Athena, a water dragon attacked but he managed to kill it. The dragon was under the jurisdiction of Ares, Harmonia's father and served him for eight years until he and the gods demanded he marries Harmonia. After their marriage, the necklace brought on many diseases upon the city of Thebes and to their family. Harmonia and Cadmus left the city and went to Illyria. In the end, Harmonia and Cadmus were both turned into serpents. Cadmus' fate was ill and reclined his fate to turn into a serpent himself just as the dragon he slain. Harmonia followed, wanting the same fate as Cadmus.
The necklace itself was continuously passed down to her daughter and future generations but all of them suffered devastating misfortunes.
Similarities to Eva and Harmonia
Harmonia brings harmony to all things, and Eva's high compatibility with the relics and the power of her voice alone bring harmony in the realm of the Vein. Her voice can calm the Lost and Successors from their frenzy (even if it's only temporary).
We have Rin who carries the Blood Code Hephaestus and Eva who has the Harmonia blood code, but they're drastically opposite to their Greek God counterparts. When Eva left home base, Rin was the one who was supposed to watch over her but was disappointed in herself for not being able to go after her. Rin was very distraught about it and was genuinely worried if Eva was okay or not. Unlike Hephaestus' spiteful nature, Rin is an absolute sweetheart and I can imagine her hugging Eva the minute she returned to Home Base safe and sound.
Based on the lore of Harmonia, we could say Cadmus is Jack as Eva is to Harmonia. Jack worked tirelessly for years after Operation Queenslayer to watch over the Relic's and Successors just as Cadmus served years under Ares service. Jack 'killed' the MC and the MC relates to the Water Dragon that Cadmus ended up killing. Both MC and the dragon were both under a rule of another, the MC taking in the Queen's blood which made them become a successor inheriting the relic and the water dragon is under Ares' jurisdiction when they ruled over certain land. Cadmus had to make up for the dragon's death while Jack had to begin his duties of being a watcher after he puts down the MC.
As mentioned, Ares ordered Cadmus to marry Eva and thus began their endeavors and their route of misfortunes when she received the necklace. While Jack gave Eva as much freedom as he could, she willingly chose to assist Jack and remain at his side, not because of obligation but she sincerely cares for him. While not much is noted of Harmonia's personality, even she remained devoted to her husband until the bitter end.
With Eva having the capacity to store many relics within her, it is also her misfortune. She is aware that carrying many relics takes a toll on her as we see her collapse while stopping Jack. However, she knows she has the power to contain them and she will do it if it lessens Jack's burden. With the Necklace of Harmonia, the city of Thebes bred disease and it also affected the people and Harmonia's family.
It relates to the Revenants in the Vein that suffers from Bloodthirst and the lack of blood beads. It also pays homage to it in the Crown of Sand area, since wherever the player or your partner steps on the sand, it immediately drains Ichor. "Leak" is a debuff in the game and it describes as: "This debuff causes your blood to rot, slowly draining your ichor." if any Revenant's blood rots then they're unable to use any abilities or Gifts which could be considered a disease in itself.
“Look, there used to be ruins here, but now they’ve been turned into a desert. the successor who created the crypt used their very last ounce of strength as they struggled to resist their relic. The wind scattered salt from a dried up lake over the land nearby, making it barren. Now it’s the same kind of desolate place as the one where Eva was born. She and I promised each other that if either of us fell to the thirst, the other would have the last of their humanity. Eva is waiting for me... just over there...I’m talking too much. anyway, i’m going on ahead. this is between me and Eva.” -Jack Rutherford
Also, regarding the relics, the main disease that Jack and Eva have to worry about is frenzy. Once frenzy hits, it's over.
Cadmus was burdened with being the founder of the city and eventually caving into his fate to become a serpent, a similar beast to the dragon he slain. Harmonia followed him and joined in with his fate. We see Eva doing this for Jack as well. Eva wasn't a Revenant yet when she met Jack and in the end after everything that transpired between both of them, Eva decides to join Jack and become a Revenant and the Successor of the Relic.
As Jack mentioned in the Crown of Sands area, Eva grew up in a similar environment. This is related to the city of Thebes that Cadmus founded. The city of Thebes is a city in a desert environment that matches well with how Eva is linked to the sands. Harmonia married to Cadmus in the City of Thebes and resided there for a decent amount of time. Eva grew up in an area similar to Thebes (we're not sure where in the real world the Vein is referenced from).
As we can see in Eva's design. Her scars are probably her physical representation of Harmonia's misfortune along with the infamous Harmonia's Necklace. While there's no official image I can reference from (cause frankly the necklace could have a vastly different design and there are various interpretations of it), Eva does wear a necklace and Jack also wear a necklace matching with her, which displays how they both are willing to share the same fate. This is a nod to Harmonia's lore.
Harmonia's Gifts
Gift Prowess-Temporarily increases gift speed for you and your partner.
This Gift as you guys can probably guess relates to Harmonia's relationship with Cadmus. Qhile many things happened during their time together, they remained together til the bitter end. They both supported eachother despite the fate and the curses that fell upon them. - Max Ichor Boost-Increases the maximum amount of ichor that can be held. Mind/Willpower Up-Increases mind and willpower.
These Gifts specifically pertain to Harmonia's necklace. While the necklace caused her misfortune, it gave her eternal youth which is the only benefit she had. Ichor is special blood that enables a Revenant to use Gifts and abilities so the more ichor a Revenant has the more versatile, and it's the same with Eva. In terms of the Mind/Willpower Up, it's within the same theory including the fact that Harmonia in Greek lore is very strong-willed to keep up with misfortune after misfortune. - Supernatural Blood-Enables you to sacrifice HP to use Gifts when you have run out of ichor.
Harmonia turned into a snake and sacrificed herself when her husband fell prey to the same fate. Harmonia did it voluntarily just like Eva voluntarily became a Revenant to support Jack. This Gift references from Harmonia's sacrifice. - Volatile Storm-Creates blades of sand that converge on the target and explode. Sand Edge-Creates a blade of high-pressurized sand from the ground that knocks away foes.
The gifts here with sand like properties relates to the city of Thebes where Harmonia's husband founded and ruled over. Harmonia was also by her husband's side and lived within the city as well. Thebes in real life is a sand-like area as well (however we don't know if Eva is really from there or not). While Harmonia was not a fighting God, she was a part of the city and these are more based on Harmonia wanting to protect her family and the people of Thebes from any threats.
Concluding thoughts
Eva is a very lovely character overall. I feel like the lore of Harmonia matches well with her and it balances out with Jack being her Cadmus in the lore. Other than the Necklace of Harmonia and how Harmonia matches with her ideals, there's not too much to expand on. The one thing I am thankful though is that her supposed 'misfortunes' weren't as severe as her Greek God counterpart. She brings a great sense of balance to the crew at home base and I don't think the story would work out without her presence. Plus her dedication to Jack is something that should be admired.