For the Straw Hats and their new pals, the last few chapters of One Piece have not gone well. Communications are down, the Snail Cams are being eliminated one by one, and the Seraphim are attempting to kill everyone while everyone is imprisoned in the Labophase. Furthermore, all of this is taking place before Kizaru and Saturn have even reached the Future Island.
The Vegapunks might contain a traitor, according to Shaka. Even while it's hard to fathom why a Vegapunk would go all Benedict Arnold, there are still around seven potential possibilities, among them the Stella. Here are the most plausible candidates, disregarding any scenarios involving Saturn, a covert eighth Vegapunk, or some other unknown component.
Which Vegapunks Are Least Likely to Be the Traitor?
The Seraphim are designed so that their orders cannot be overridden by someone of the same level of authority; they can only be handed new orders by someone on a higher level of authority or a lower level if the person who gave the order is rendered unconscious. Therefore, if one of the Vegapunks fails to make the Seraphim stop attacking, they can't be the traitor; this might change if it's revealed that the renegade Vegapunk was suicidal enough to order the Seraphim not to follow their next command, but that's yet to be revealed. For now, this is the best clue for readers to go off of.
So far, a few Vegapunk Satellites have been shown trying and failing to rein in the Seraphim. Lilith and Shaka explicitly tried and failed to order them to stop, so they were cleared of suspicion. Pythagoras also reportedly failed to order S-Snake to stop, though he wasn't shown doing this. York also mentioned Edison's orders to S-Snake before she was petrified, though this could be seen as more of a review of the facts than a direct order. Ideally, this should mean that all four of these Satellites are cleared of suspicion.
Regrettably, there are still some problems with Pythagoras and York's accounts. Despite the fact that they were both attacked, this might have been the intended outcome. Pythagoras could "happily live" with just his head, and York could be unfrightened after everyone else has died if either of them had covertly instructed S-Snake to attack or even "eliminate" them so no one would suspect them. These are among the most unsettling because they were the first two Satellites to be assaulted.
Atlas is mostly clear of blame, but not because of any interaction with the Seraphim. She was being repaired when the Frontier Dome defense system shut off in Chapter 1071, "The Hero Deploys." She might have snuck off to shut these defenses off when no one was looking, but she at least has this alibi for what it's worth.
Which Vegapunks Have the Most Chance of Betraying the Clan?
Even if it's hard to imagine, the primary Vegapunk is one of the people who is most likely to have put everything up. As the Frontier Dome was shut down, he was also noticeably missing. Jewelry Bonney later discovered him while she was frantically searching the lab's interior for him. He also completely disappeared about the time the Labophase was locked off, thus he will need to account for his disappearance once he is located. He's still not the member of Vegapunk that the fans are most wary of, though.
Of the seven Vegapunks, Edison is the most suspicious. He, too, was absent when the Frontier Dome was turned off and possibly when control was lost; while attention has been drawn to the fact that the Stella has been missing in these events, Edison is equally suspicious. He was also the last one to give the Seraphim an order, so he should still be the one in charge; again, his being attacked might have been part of the plan. It's not a lot to go on, but it's more than most of the other Vegapunks.
We still don't know why Edison would do any of this. Seeing additional Vegapunks being attacked, learning where the Stella is, or simply learning more about the Vegapunks or the Seraphim could all help to explain this. Edison is the most likely suspect to be the traitor right now.