You know, I think people sometimes overlook the older stuff in this subgenre, but I keep going back to Suzanne Wright's 'Dark in You' series—wait, that's demons, sorry, got my wires crossed. For wolf packs specifically, her 'Phoenix Pack' and 'Mercury Pack' books are basically the blueprint for that hyper-focused, 'us against the world' loyalty. The bonds aren't just a background element; they're the plot engine. Characters like Trey and his pack in 'Feral Sins' have that brutal, unwavering protectiveness that borders on problematic if you think about it too much, but it's so addictive to read.
A lot of newer romantasy tries to make the pack dynamics more politically nuanced, which is cool, but it often loses that raw, primal intensity. I recently tried 'The Tyrant Alpha's Rejected Mate' and while the angst was top-tier, the pack itself felt a bit like set dressing. The loyalty was all directed at the romantic couple, not the wider group. For me, the classic shifter series from the early 2010s still do the 'pack as family' thing best—flaws and all, they built that claustrophobic, all-consuming sense of belonging.