Spoilers below for both The Walking Dead's finale and part of the comic book's storylines.
Throughout The Walking Dead Season 9, Eugene has basically spent his post-Savior existence doing two things: pining after Rosita, and developing a form of inter-community communication. His efforts were shown to have come to full fruition in the snow-capped finale, with the Hilltop-settled Ezekiel sharing his story via shortwave radio with Judith in Alexandria. Celebrations aside, the more shocking moment occurred soon after, when someone else's voice came through the radio. Dun-dun-dun!
Though the transmission was static-filled, this was what came through the speaker:
Hello? Hello? Calling out live on the open air. Is anybody out there?
Many viewers were likely shocked to hear a new voice, including the comic readers who assumed that such a moment would occur at some point down the line. I'm guessing everybody would love to know what's going to happen next, too, since there's unlimited potential to be found in the prospect of another radio-friendly community existing out there somewhere.
Before diving into what the comics can tell us about this big moment, check out what Walking Dead showrunner Angela Kang told me about it.
You know, it's like, I can't spoil anything related to that. [laughs] But I'll say that when a mysterious radio voice is out there looking for people. I mean, we gotta do something with that story, right? So there will be some answers that happen in the next season, and it may or may not be what people expect. It should be a lot of fun, though. Knock on wood.
Considering we're still around seven months from the start of Season 10, it's to be expected that Angela Kang needs to stay mum about where any storylines might be headed regarding the radio's mystery caller. It's entirely possible that the voice might become the next recurring mystery for fans to wonder about, similar to the helicopter enigma, which still hasn't been fully explained.
Thankfully, we can fall back on the Walking Dead comic books to give us an idea of where the TV series could be heading with this leg of the storyline.
What We Know From The Comics
The first big distinction between the TV show and the comic book narrative is the fact that no one heard the radio call in the Season 9 finale, while Eugene was sitting at the radio when the mystery voice came through on the page. That's already a wrench in the works for the TV characters, since it's not clear when or if anyone will ever be around to hear and respond to a call.
Eugene and his female radio contact don't immediately start sharing their deepest darkest secrets or anything, but their initial conversations are comfortable and easygoing. Despite that, a sense of creeping paranoia cloaks much of their communication process, since it's extremely rare for good things to come from sharing personal details with strangers. Especially in this universe.
Eugene soon explained Team Family's troubles with the Whisperers to the woman, sharing that they'd killed Rosita, who was his pregnant-for-another-man girlfriend in the comics. Feeling sympathetic, the woman chose then to reveal to Eugene that her name is Stephanie. And it's not much longer before each shared the location of their respective communities, with Stephanie's being somewhere within Ohio. (Start looking for those Ohio clues soon!)
Stephanie's story definitely develops and evolves beyond this in the source material, but it's not that likely that the TV show will reach this narrative point during Season 10. The TV show's protagonists are destined for a larger fight against the Whisperers, which the TV timeline mostly matching up with the comics', so there may not be much time for radio communication if everyone is caught up in the throes of battle.
Stephanie does end up being a trustworthy ally for the team, but that doesn't guarantee everything, or anything, will go the same way for the TV characters. Angela Kang and her creative team might very well decide to put a more villainous character on the other end of the radio. Someone that can take advantage of a lovesick Eugene in order to get him to reveal sensitive information about Alexandria and Hilltop.
Regardless of whether or not the radio voice belongs to somebody that TV audiences will be able to trust, I just hope that person is the link that will connect Michonne and Alexandria back to Rick, and also then to Jadis and maybe even Heath. Granted, that stuff would likely play out in the upcoming standalone movies and not on the series, but the hope still remains.