Accordingly (and much to my delight), he and Cora have actually become much more closely bonded over the past few months. As some may recall, Coraline and Brodie were actually adopted three weeks before Shadow simply due to the uncertainty inherent in trapping from a feral colony.
Brodie and Shadow got along famously from the moment the brothers were re-united, but Cora spent the first few weeks after her briefly-estranged sibling's arrival hissing and growling at him whenever he entered her sight. Eventually she came to accept him, but for ages she and Shadow were both closer friends with Brodie than with each other. Now, though, I'm seeing something different in shape but equal in (positive) magnitude developing between this particular sibling pair.
(Above image - Cora surveys the yard this past weekend, when I let her and Shadow out to run around a bit while I worked on my laptop on the patio.)
Brodie remains the go-to sibling for cuddles and free ear-washing (and the occasional but vigorous round of CHASEWRESTLEGRR, which even cats of the Garfield persuasion enjoy sometimes) but Cora has definitely gotten to the point where she knows that if she needs a partner in mischief or someone to tear randomly around the house with, Shadow is her guy.
It's also been neat seeing these two teach each other things. Cora has always been the most mechanically inclined and apt to experiment with objects of her own accord, while Shadow took months longer than either of his siblings to get to where he'd (for instance) bat treat-puzzle balls around just-so to dispense the crunchies within. It wasn't that he lacked the brainpower to operate the treat puzzles -- he's just always had the natural predisposition toward persuading others to do things for him (a trait he actually shares with Nikki).
Lately, though, he seems to have come around to the idea that there are some things he can better accomplish without running immediately to ask for help. E.g., he's become quite the expert at opening any door that isn't latched, and has managed to sneak into the bedroom behind me quite a few times recently!
(Above image - Shadow rests a while in the leaves after a vigorous game of Garden Tag with Cora. None of the kitties here have unrestricted outdoor access but on nice days these two really appreciate a chance to run off some of their energy in the back garden.)
Cora, in turn, seems to have experienced something of an epiphany in the opposite direction, as she seems to have become a lot more vocal all of a sudden, and has even adopted some of Shadow's "super secret weapons of human persuasion" (such as what I refer to as the "kittens of the damned stare" in addition to the "Lassie move" where the cat basically orders the human into a different part of the house and looks pointedly at the thing they're interested in, which in Cora's case is usually the back door!).
Of course both of these kitties have maintained their innate inclinations toward Explorer/Engineer (Cora) and Mr. Charisma (Shadow), but it's abundantly apparent that their growing friendship has led to a really neat expansion of both of their respective skill-sets. Which is just super cool to see.