This article contains spoilers for Phoenix Song: Echo #1.
Alaqua Cox is bringing Echo to life in the Marvel Cinematic Universe - but in the comics, the superhero has taken possession of the Phoenix Force and is at risk of turning full Dark Phoenix. The MCU is expanding at a prodigious rate, and the Hawkeye Disney+ TV series is set to introduce a whole new vigilante - Echo, the woman who adopted his Ronin identity in the comics. Alaqua Cox has been cast for the role, and she's then set to star in her own spinoff. This could well give the MCU the Ronin story Avengers: Endgame failed to deliver, because if Echo remains active as Ronin, she'll be a very different kind of superhero - one who's a whole lot more brutal.
Naturally, Marvel Comics is eager to take advantage of this to establish a bit of synergy. They're not trying to mimic the MCU, though, but rather simply increase Echo's profile - in the most surprising way. She has become the host of the cosmic Phoenix Force, an entity of death and rebirth. As the goddess Hela explained, "Existence is binary. Alpha-Omega. Chaos-Order. Beginning-End. Life-Death. Phoenix is the passion of creation. Dark Phoenix, the cold fire that brings it to its end." The destructive impulses tend to overwhelm hosts, resulting in many of them going Dark Phoenix.
And Echo is, unfortunately, going full Dark Phoenix. Phoenix Song: Echo #1, by Rebecca Roanhorse and Luca Maresca, sees her intervene in a robbery in Hell's Kitchen. One thug holds a gun to the back of her head, and Echo responds with a flare of Phoenix power that literally burns him alive. The others run, and a furious Echo can't help roaring her fury at the heavens - unwittingly starting a fire that burns the building down. Horrifically, a child in a room upstairs is almost killed.
This is the problem of the Phoenix Force; it amplifies everything that is already there, the good and the bad, the strength and the weakness. Every single emotion bubbles to the surface; a moment of rage becomes a firestorm that can consume an entire star. Echo flees to the Moon for peace and solitude to reflect; an ironic place to go for sanctuary, given the original "Dark Phoenix Saga" came to a climax on the Moon, when Jean Grey's humanity led her to commit suicide rather than unleash Dark Phoenix once again.
Apparently, the Phoenix Force has chosen Echo as its host for a reason, though; because it sensed she was facing a terrible threat, one that could erase her from existence. Ironically this may well prove to be Echo's salvation, because an enemy will allow her to choose a target for the full power of the Phoenix Force. Hopefully, that sense of direction will give her the self-control Echo needs to resist the siren song of Dark Phoenix's power.