“Stranger Things 2” is the middle school-aged older brother of season one; it’s all the wholesome geekiness and heartwarming friendship of a stereotypically ’80s childhood, but it’s getting more interested in girls.

The signs of age are everywhere, from the blossoming of Eleven’s (Millie Bobby Brown) buzz cut into a mane of curls (I get Ally Sheedy in “The Breakfast Club” vibes) to Dustin’s (Gaten Matarazzo) new set of pearly whites. And beyond the physical and emotional implications of growing up, our Goonies-esque gang is facing all new intriguing dynamics. Most notably, Eleven isn’t around to stupefy the boys with her telekinetic powers, and Will (Noah Schnapp) is no longer siloed in the embryonic goo of the Upside Down. 

But show creators Matt and Ross Duffer are quick to reestablish season one’s winning chemistry: the boys have a new girl, Max (Sadie Sink), to stupefy them — this time with nonchalant grit and radical kick flips — and Will remains the painfully suffering, sallow-faced victim he always seems to be, now in more domestic settings. 

What the Duffer brothers couldn’t write away — the gang’s inevitable transition to pubescence — they made pivotal to this season’s tug at our heartstrings. We relate to the woeful ploy of the geek after a cool girl, and the trepidation of attaining a well-coiffed mullet for the school dance. And when said geek doesn’t get said cool girl despite his well-coiffed mullet, we shed maternal tears (or I did, at least).

The everyday social terrors of fitting in even get a cheeky horror treatment, true to Duffer form. In episode two, which sees the boys don “Ghostbusters” garb to school on Halloween, a terrified Dustin turns slowly toward an unseen danger — electronic music intensifying, courtesy of S U R V I V E — only to demand, “Why is no one else wearing costumes?” We laugh, but that stuff is terrifying. “When do people make these decisions?” Dustin wails, echoing the traumatic confusion our thirteen-year-old selves knew all too well.

One of the foremost virtues of this season is its saturation with genius despite unlikely character pairs. Police chief Hopper (David Harbour) is secretly housing Eleven in his eerily isolated but kind of cozy shack-in-the-woods, where a newfound paternal softness glows through his bear-like exterior as the two share TV dinners (and Eggos du jour). But as moody preteen Eleven reels against her sugar-coated imprisonment, power clashes with power. A luxuriously cinematic psycho-tantrum punctuates their fuzzy relationship with window-shattering and furniture-throwing à la “Poltergeist,” as terrifying as it is heartbreaking.

Another unlikely pair arises when a desperate Dustin beseeches cool teen Steve Harrington (Joe Keery) to help defeat a loose baby Demogorgon-dog (just watch it). The two form an adorably ironic mentorship along the monster-hunt, prompting Steve to share even his best kept hair secrets — specifically, four puffs of Farrah Fawcett spray — with his budding protégé as the two trek down the train tracks in a scene with whispers of Rob Reiner’s “Stand by Me.” 

Season two also boasts brand new villains; the Demogorgon has been one-upped by a Lovecraftian monster-god labeled the “Mind Flayer,” in keeping with “D&D” lore. This new horror takes hold of Will’s mind early on in the season, leading to a lot of “Exorcist”-esque convulsions which, for all their exhilarating horror, render Will’s story a little tedious and unengaging.

While season one was replete with human villains, pretty much everyone has either become a Demogorgon snack by this season’s premiere or turned a corner and found that their hearts have grown three sizes. And in the absence of maniacal scientists, the Duffers are quick to write in a new human antagonist as Max’s older step-brother, an ’80s bad-boy archetype. Billy (Dacre Montgomery) is all the stomach-turning charm and erratic rampage we despise. Even a poignant glimpse into his turbulent home life isn’t enough to forgive his brutal beating of Steve late in the season. Montgomery’s madness is perfectly believable and wholly chilling.

But season two contains a pretty major misstep: the troubling subplot of Eleven’s estranged sister-in-telekinetic-power, Kali (Linnaea Berthelsen). Eleven’s powers guide her solo journey to Chicago, where she finds Kali in a rough-and-tumble crime gang and promptly becomes badass-ized. The new look is cute and all, but the stand-alone episode devoted to the subplot feels totally out of touch; the writing is lackluster, the characters irrelevant, and where are my lovable misfit adolescents? The Duffers may have set up avenues for future storylines but at an undue expense to this season’s coherence.

Aside from this hiccup, season two preserves the allusive and idiosyncratic magic of “Stranger Things.” The ’80s are everywhere, from Reagan yard signs to Radio Shack. As always, Will is sick, Mike is sad, Dustin is hilarious and Joyce (Winona Ryder) is harrowed. We get what we know and love, just a little grown up. And this hint of lower voices and hormonal confusion is utterly embraceable.