Cable's younger self, Nate, was resurrected by Cable as his sidekick, signifying a dramatic shift in their tumultuous relationship. Nate had previously killed Cable, believing it threatened the timeline, but now they had reconciled and were working together. Cable saved Nate's life as a gesture of gratitude for Nate's earlier efforts to resurrect him. This act allowed them to start anew on an extraordinary adventure.
Cyclops' son, Cable, just recruited himself as a sidekick, adding another member to the Summers family. Based on his Marvel Comics history, this choice is a shocking and unexpected one.
After flipping past the cover that features Cable the way fans love him most (classic suit, giant guns, generally badass), the book opens with Nathan chopping through Orchis goons like it’s nothing, searching for his younger self. Finally, Cable tracks Nate - who now goes simply by ‘Nate’ - to a shipping container vessel where Orchis is covertly hiding and studying him. While it seems Orchis already derived a great deal of intel from Nate (which will undoubtedly be the crux of the protagonists’ struggles moving forward), Cable does greet his younger self when he finds him, meaning Nate is alive and Cable has effectively taken Kid Cable on as his sidekick.
The fact that Cable decided to recruit Kid Cable as his sidekick actually reveals how far the two characters have come since their first interaction. In Extermination #1 by Ed Brisson and Pepe Larraz, Nate tracks down and murders Cable in cold blood. Kid Cable recognized that his older self was damaging the timeline, and he needed to be stopped. When Nate finds Cable, he mercilessly tells him, “You’re no longer the Cable I know, and I won’t hesitate to finish what I started.” From that point forward, Kid Cable was the main version of Nathan Summers who existed in the X-Men canon throughout the majority of the Krakoan Era, and he continues to play a significant role to this day - as evidenced by this preview.
While it may seem shocking that Cable would get over his own murder by not only recruiting Kid Cable to be his sidekick, but by saving his life at all, that’s actually ancient history between the two of them. In fact, Cable saving Nate’s life like this is basically just him returning the favor. In Cable Vol. 4 #11 by Gerry Duggan and Phil Noto, Nate pushes for the resurrection of his older self on Krakoa, even though that meant he’d lose resurrection rights himself upon his death. Nate waived his rights to future resurrections to get Cable back for a specific mission involving Stryfe, and the older Cable has been back ever since. Now, Cable has returned that favor to his younger self by saving his life in this issue, allowing them to start fresh on an all-new adventure.
Cable's relationship with his younger self (and, indeed, every facet of his entire life) is unarguably weird, especially now that they are going to be working together. But, at least it's healthier than it was originally, as both versions of Cyclops' son are now able to get along, solidifying that fact in the X-Men canon.