Now I'm just hoping for an "oops, all parents" au where for some reason or another every member of z-team has a kid
I spent some time figuring out who'd have bio or adopted kids, who's more of an aunt/uncle/big sibling figure, and I think I got it down. Went back to an older post I made where I discussed how good each character probably is with kids.
Robert: Currently pregnant (as per normal in my aus), and/or has a certain shape-shifting toddler (Abigail). Won't reveal who the other parent is. Basically the protagonist of an otome game rn.
Sonar/Victor: Werewolf baby. One of Victor's first ever big missions was to enter a suspected dog-fighting ring - only to find out that the ultimate prize was in fact a baby werewolf/wolf hybrid. Victor doesn't want to think what the baby's fate was going to be if him and SDN didn't step in. Artemis "Artie" is a healthy, if destructive puppy of a two year old, who loves their big scary bat-dad very much. Has zero fear of Victor's megabat form.
Flambae/Chad: Primary guardian of his sibling's kid; whether due to sickness, imprisonment, or death in the family. Struggling with being both the fun uncle and responsible father-figure to his niece. May or may not be the same niece he attends dance recitals for. Parisa is combative little girl with Ifrit heritage, able to fly using wings of fire. She loves her uncle, but is still emotionally grappling with the loss of her parent and often lashes out at him. Latches on to Mecha Man as her favourite hero, feeling a connection with his own well-known losses.
Invisigal/Courtney: Accidentally acquired a Lil shithead kid dragged into Red Ring gang. Courtney strikes me as very much a big-sister figure, but she would be very protective of any kid she considered Hers. Tiano was yet another kid without a family, drawn in by the Red Ring's promises of camaraderie and aid. His powers grant him the ability to see heat signatures - and nothing else. Tiano did minor scouting and delivery jobs for the Red Ring in hopes of eventually gaining a sight augment. He was made to shadow Courtney, with the invisible thief acting as his mentor and big-sister. After the Mecha Man explosion, Courtney packed everything up and took Tiano with her. Tiano is as about as disrespectful and emotionally unstable as a kid being raised by criminals could be, but he's getting better. Relationship with Courtney is fractured - he sees her leaving the Red Ring as a form of betrayal to their criminal family. Has reptilian features.
Punch Up/Colm: Stole Adopted a hybrid kid from the circus freakshow. When Colm was cursed, he knew that his days as a strongman were limited, so he took off to adapt to his new height/abled status. Sometime after meeting Coupe, he decided to revisit the same circus to see how things were getting on. There he met the new star attraction. Muirgen is a seal hybrid sold to the carnival freakshow as a toddler due to their limited mobility and specialised needs. Colm decided that wasn't on, and asked Coupe help him with the adoption - i.e. kidnapping the toddler from the circus, forging adoption papers, and sneaking them into America. Muirgen is currently a cheerful preteen boy with mobility aids, already taller than his dear Da. Idolises hybrid superheroes.
Prism/Alice: Proud mom of a very spoiled (and fashionable) bay girl named Cadence. Baby was the result of a messy ex-relationship that Alice is happy to put in the past. Keeps her daughter separated from her super identity as much as possible, save for a rare interview where Cadence was still very young - wearing a miniature version of her mama's hero outfit. Cadence is currently three years old and holds more confidence than half the adults in SDN.
Golem/Bruno: Baby Kaiju he names Pebble. Same one Z-Team encounters on the job. Pebble is a marine kaiju, so she needs a lot of time in the water. Bruno and Herman regularly meet up so their guppies can swim together.
Coupe/Janelle: Discovered that a little girl was being groomed by the mob to become an assassin like she had been. Janelle killed the leaders of the program and unofficially adopted the girl as her own. Odile is an unsettling little girl, albinistic (white hair, pearly skin, red eyes etc) sans her black wings. Odile is gradually opening up to being a little kid again. Loves fairytales and cartoons about princesses.
Waterboy/Herman: Has his lil waterbaby Kai from this au idea! College sweetheart dipped after the baby was born, leaving Herman sole custody. Kai is an axolotl/tadpole-shaped baby, who's very picky about who holds him. Herman is very tired but happy.
Phenomaman/Katon-Ur: Has an adopted daughter. Some time ago, a pod from the planet Urgot-52bc landed on Earth containing a single large egg and a note. Phenomaman was contacted to discern the pod's contents, and with a mournful expression held the egg in his arms. "She has been abandoned. They call her Unwanted. What a terrible thing to call a child." He then publically announced his adoption of the alien egg-soon-a-baby. Nova hatches into an odd-looking baby during the course of the canon timeline, but the others treat her the same as any other of their kids. Nova hasn't figured out how to fly yet, only float an inch or so off the ground.
Blonde Blazer/Mandy: Met an orphaned kid with high heroic potential, and accidentally did a Batman and adopted them. Blazer responded to a villain attack where a child named Sherry was left orphaned, leaving the kid in judicial limbo until the villain responsible was caught. Through interacting with Sherry in civilian-mode, Mandy became very attached to them. Mandy agreed to take on Sherry, not only as an adoptive parent but also as a heroic mentor. Sherry does not have an amulet of their own, but has a whole concept folder of their future heroic persona; Scarlet Blazer - named for their bright red hair. Very nerdy about getting to meet the Mecha Man.
Royd/Roy: After a few years in the Phoenix Programme, Royd decided he wanted to make the plunge and become a foster parent. As the program saw potential in him, he wants to see realised in at-risk kids. Current foster kid may become a "foster fail" aka full adoption. Hokulani is seven years old, and was the target of significant discrimination in their last group home due to their island heritage. Still very stand-offish towards others, but is interested in marine exploration.
Trackstar/Chase: He has Robert. Also may or may not be Pom Pom's father/relative/mentor as per this post. Is an adoring, proud dad figure who swears he's not spoiling them (he is).