In the final act of Eternals, it was revealed that Ikaris killed Ajak and was aware of Arishem's plan for a new Celestial, Tiamut, to emerge from Earth (destroying it in the process). Ultimately, Ikaris couldn't bring himself to deliver a killing blow to Sersi and helped his fellow immortals stop the emergence before seemingly flying into the sun to end his own life.
Some fans have questioned whether Ikaris actually died; we didn't technically see his demise, and there's surely a chance the hero turned villain changed his mind or was even stopped by Arishem.
Nope.
Talking to CBR, writer Kaz Firpo confirmed that Ikaris is dead and gone. "What is the melting point of an Eternal? How long does it take to literally melt an Eternal robot? For what it's worth...yeah, it was always that. He can't bear to face his family after what he's done, which he realizes."
"I don't think that Ikaris even thinks that he's wrong," the Eternals screenwriter continued. "I think that he just has so much regret. He's very sorry. I think he's sorry for the way he lived his whole life on this planet, and that's a lot of burden to carry. So really, that act is basically saying, 'I made a mistake, but I can't face my family, and I can't go on living.'"
"It began as an exile that I think, throughout the course of the filmmaking, really became something that needed to be definitive. It really is a moment of saying, 'It's sacrifice.; It's sort of saying, 'I can't serve the Eternals. If I can't serve the Celestials, and I can't be with my family, then I choose this third option,' which -- for him -- really is oblivion. So yeah, he dead."
It definitely sounds like there was a version of Eternals where Ikaris lived, but it's easy enough to understand why the story went in this direction instead. We can't help but be disappointed that Richard Madden was a one and done in the MCU, but flashbacks likely mean he can still return in some form.
Check out our interview with Arishem voice actor David Kaye below: