Eternals introduced more than a dozen new characters to the star-spanning film version of the believed Marvel heroes, and it just so happens that one of them is a Titan prince. Eros is now a member of the Marvel Cinematic Universe, and while his inclusion brings narrative opportunities, it also provides significant potential pitfalls if the character is not handled with extreme care. With that in mind, let's look at where Eros and his brother Thanos come from, their connection to the Eternals of Earth, Eros' unsavory past and how all of this presents unique challenges for any serious adaptation of the character.
Throughout their million-year history, the Eternals have fought two civil wars, and Eros is the product, both directly and indirectly, of both of them. The first took place 600,000 years ago and was called the Uranosian War, fought between Uranos, who believed their god-like abilities justified their conquest of mortal man and Deviant alike, and Kronos, a pacifist who believed contemplation and study by beings as advanced as the Eternals could accumulate knowledge and foster peace. Uranos lost in single combat to Kronos and was banished from the Earth along with his followers, whose only regret was that they had lost. In exile, a small number of survivors made their way to Saturn's largest moon, Titan, and built a metropolitan civilization. Unfortunately, that was destroyed by war as well, and the conflict left only one person alive -- Sui-San, mother to Eros and his old brother Thanos.
The second Eternal Civil War, 200,000 years ago, dealt with an ideological dispute concerning whether or not the Eternals should tamper with their physiology so that they might have biological offspring since the Celestials who created them did not include reproductive capacity. Another set of brothers, in the familial but not biological sense, diverged greatly on the answer to this question. Zuras believed that the Space Gods probably had a reason for not equipping their race with the ability to genetically propagate, while A'lars believed that his research into the matter should continue unimpeded so that they could realize their ultimate potential as a species. After bloodshed and mediation, A'lars was banished so that could explore his theories without influencing the Eternals of Earth. He then sought out Titan and found Sui-San there.
Children of exiles from the only two wars the Eternals have ever known, Thanos and Eros represent the ultimate failure and success of A'lars' dream, who became known as Mentor once he emigrated to Titan. Thanos was born with a Deviant mutation and singular genius that set him apart from all other Eternals and engendered a certain desire for distance, while Eros was born with all the potential of his forebears and a unique ability which brought ambient comfort to those around him, drawing people to him. When he focuses on this effect, he can psionically induce pleasure centers in the minds of others to varying degrees of intensity. Eros visited Earth during its early civilizations, and much like its native Eternals, he allowed mankind to deify him, hence the Greek god of the same name.
Eros later teams up with the Avengers during Thanos' first flirtation with omnipotence, and sometime after defeating the Mad Titan, he returns to Earth to join the Avengers on the same day their resident Iron Man resigned. Given the name Starfox, he becomes a rotating member of the team. He was there when Sersi was recruited, and during that adventure, found out about his connection to the Eternals of Earth and joined the Uni-Mind for the first time.
Thanos continued his dalliance with godhood after acquiring the powers of the Phoenix Force and Eros was instrumental once again in defeating him, but even after death, his threat remained. Thanos prophesied his reincarnation in another form, and in an attempt to stop that from happening and end the threat of his universal slaughter once and for all, Eros led a campaign to kill the one person he thought Thanos would choose as his vessel, his adopted daughter Gamora. However, it was actually Eros who had been chosen, and Thanos successfully possessed him until uniting with a body designed to hold his power and intellect. It has since been established that, once a year, Eros and Thanos meet at the edge of the universe and exchange gifts with one another as an ongoing reminder of their relationship.
However, despite fighting for the side of good, Eros has seen his fair share of controversy. A pivotal moment for the character occurs when he is accused of sexual assault by a married woman who believes that she never would have seduced him had it not been for the influence of his natural abilities. Defended by She-Hulk, the attorney of record for almost all superpowered individuals in need of an advocate, the story is further complicated because of a one-night stand they once shared and the confusion about the circumstances of her choices that evening in light of the allegations. Though the comics provided an answer to the latter, it never fully addresses the former, and even in She-Hulk's case, the answer is extremely problematic. Eros did not use his abilities on her during their night of intimacy, but he did unknowingly use his powers on her without her consent in regards to her husband prior to their marriage because he thought it would make her happy.
One of the noteworthy aspects of this part of the lore is the decision of the Avengers to either publicly defend, shun or remain neutral in the proceedings. Out of the eight active Avengers at the time, four of them outright refused for different reasons, two enthusiastically decided to come to his defense, one was undecided and the last was noncommittal. Of those eight, only the Wasp and Captain Marvel have been introduced into the MCU, and their decisions within the comics continuity in no way binds their cinematic counterparts to any position, but it is interesting that Eros was so divisive among a group of men and women who had fought alongside him against threats that could destroy all of existence.
Another important moment for Eros is when Thanos comes to testify on his behalf when the trial relocates from the streets of New York to the moon of Titan. She-Hulk is drafted into service by the Living Tribunal to stand as an impartial observer of the proceedings, and Moondragon uses her telepathy to discern irrefutable testimony from even subconscious deceit. In so doing, it is revealed that, as children, Thanos and Eros were playing when Thanos unintentionally killed a wild animal he had embraced without taking into account his own natural strength. In an effort to console his brother, Eros used his abilities to help him embrace death as part of the natural cycle, which Thanos considered the moment of clarity that set him on his path of genocide.
This instance of Eros' history offers a swath of narrative potential but also opens up the MCU to issues of consent and sexual dominance that seem ill-suited to the types of stories it wants to tell. On the one hand, a character who is in every way affable and charming but who also carries a profound sense of guilt over the part he played in the Infinity Saga, however unwittingly, is compelling. This would allow for a character who is in so many ways a relic of another time to have depth and thoughtful consideration about the uses of power and the consequences inherent to beings who traffic in the far-flung miracles and tragedies incumbent to galactic heroism or villainy. However, that all depends greatly on how his powers are portrayed, or if they are changed to allow for clear black and white considerations.
To see Eros' MCU debut, Eternals is streaming now on Disney+.