The Roman Gods are the more disciplined, militaristic and warlike version of their Greek counterparts. However, for primordials, the change is nonexistent as they are the embodiments of their domains. They are also less laid back.
Though belonging to the same race of the Greek Gods, the Roman Gods as numerous differences of their original counterparts due to the more formal and serious vision that the Romans had from them. Due to being seen as more mysterious and dedicated to their roles than the Greek Gods, they do not visit their Demigod offspring and mortals very often, nor do they have many children with mortals, unlike that of their Greek forms. The Roman version of the Greek Gods are also more skilled in the ways of combat, and seem to care more about honor than personal code, matching with the Roman culture. Some Roman Gods do not even have a Greek aspect, being born within the Roman religion which, such as Terminus, the original pure Roman God. Mithras is an instance that Roman mythology interacted and fused with other religions with the expansion of the empire. However, even the original gods can have distinct behaviors on their Roman form. This is evident in The Lost Hero, where Clovis mentions that if he had to meet Juno, he would prefer her as Hera rather than Juno, and also that Somnus (Hypnos's Roman form) killed those who would sleep during their work, unlike his Greek form who is extremely lazy.
Clovis explained that the reason of such different behavior is because the Gods' Roman counterparts are more disciplined and warlike, and therefore stricter than their Greek aspects. He also went on to claim that some Gods' behavior can be so different in their Roman form that, rather than being a distinct aspect, they may became a distinct personality of such Gods. This is evident on Mars, who is a dedicated strategist and dislikes unnecessary bloodshed, in stark contrast to Ares, his true Greek form, who loves the idea of combat and violence. Also, as shown in The Son of Neptune some Greek Gods become less respected when they are transitioned to a Roman form. In the case of Poseidon becoming Neptune, the Romans tended to fear the sea and so Neptune was less respected. Also shown, some Gods become more respected such as Mars who is respected to the point where only Jupiter is considered above him. As a result of this transition between aspects, the Gods' domain can either change or become more dominant than others as the case of Neptune being more focused on horses rather than the Sea (as Poseidon) and Pluto being more focused on riches rather than the underworld (as Hades).
However, as revealed in The Mark of Athena, there are some Gods/Goddesses that have so few different changes between Greek and Roman even they don't consider themselves changed. For example, Nemesis and Aphrodite/Venus state that because Revenge and Love are universal they don't change between their different aspects at all. Heracles/Hercules mentioned as well that he didn't feel that he had been changed very much between his Greek and Roman aspects although most people refer to him by his Roman aspect "Hercules".
It is noted in The House of Hades that minor Gods and Goddesses are less affected if there is a war between Greek and Roman aspects with only mild headaches as a result of less prayers and worship.
In The Blood of Olympus it was revealed that Artemis and Apollo could escape going crazy during the war between Greek and Roman children by going to their birthplace Delos. However leaving the area would cause them to lose control and have their powers nullified.
Unlike Egyptian Gods, the Romans have demigod children. They also have a camp where the children train like the Greek Gods. It is stated that the Romans are not as involved with their mortal offspring as their Greek counterparts. They can walk the mortal world without a host unlike the Egyptians.
- Apollo (Greek Form: Apollo)
- Bacchus (Greek Form: Dionysus)
- Ceres (Greek Form: Demeter)
- Diana (Greek Form: Artemis)
- Juno (Greek Form: Hera)
- Jupiter or Jove (Greek Form: Zeus)
- Mars (Greek Form: Ares)
- Mercury (Greek Form: Hermes)
- Minerva (Greek Form: Athena)
- Neptune (Greek Form: Poseidon)
- Pluto (Greek Form: Hades)
- Venus (Greek Form: Aphrodite)
- Vesta (Greek Form: Hestia)
- Vulcan (Greek Form: Hephaestus)
- Aeolus (Greek Form: Aeolus)
- Aquilon (Greek Form: Boreas)
- Arcus (Greek Form: Iris)
- Aesculapius (Greek Form: Asclepius)
- Auster (Greek Form: Notus)
- Cupid (Greek Form: Eros)
- Discordia (Greek Form: Eris)
- Faunus (Greek Form: Pan)
- Favonius (Greek Form: Zephyrus)
- Fortuna (Greek Form: Tyche)
- Hercules (Greek Form: Heracles)
- Invidia (Greek Form: Nemesis)
- Juventas (Greek Form: Hebe)
- Letus (Greek Form: Thanatos)
- Metus/Terror (Greek Form: Deimos)
- Portunus (Greek Form: Palaemon)
- Proserpina (Greek Form: Persephone)
- Salacia (Greek Form: Amphitrite)
- Somnia (Greek Form: Morpheus)
- Somnus (Greek Form: Hypnos)
- Spes (Greek Form: Elpis)
- Timor/Fear (Greek form: Phobos)
- Trivia (Greek Form: Hecate)
- Victoria (Greek Form: Nike)
- Aurora (Greek Form: Eos)
- Coeus (Greek Form: Koios)
- Crius (Greek Form: Krios)
- Hyperion (Greek Form: Hyperion)
- Luna (Greek Form: Selene)
- Ocean (Greek Form: Oceanus)
- Ops (Greek form: Rhea)
- Saturn (Greek Form: Kronos)
- Sol (Greek Form: Helios)
- Nox (Greek Form: Nyx)
- Tartarus (Greek Form: Tartarus)
- Terra (Greek Form: Gaea)
- Caelus (Greek Form: Ouranos)
- Typhoeus (Greek Form: Typhon)
- Fauns (Greek Form: Satyrs)
- Venti (Greek Form: Anemoi Thuellai)
- Sphinge (Greek Form: Sphinx)
- The twelve Olympians in Roman mythology are called the Dii Consentes.