Robert/Mandy Timeloop

Robert and Mandy are close in age, so the first event is between them, when Robert's about 19? It's a timeloop, that starts about the time his dad dies.

Timeloop lasts a few days, maybe a week — long enough he keeps experiencing the funeral, and Chase's condolences like a broken record. This kind of predictability can make people feel like NPCs; it eats away at the emotional depth of their relationship, and becomes really grating, which is why Robert ghosts him after.

He's feeling isolated and alone the first few loops, reliving the worst week of his life. Mandy's aware of the timeloop, but not who she shares it with, so it takes them a while to find each other. She definitely sees the news about Mecha Man's death, and either notices discrepancies in the funeral scheduling, or what was reported (ripple effects of Robert's behaviour, and the impact on people like Chase/Track Star, who were probably interviewed), so she decides to check it out.

Robert keeps trying to save his dad, but he just isn't close enough at the start of the loop to do anything in time, and Mandy has to help him come to terms with the fact it's not going to be prevented, and this loop isn't about his father.

Robert starts getting practice in as Mecha Man, so he has some experience under his belt by the time the loop breaks. The loops give them time together, but it also gives them direction and purpose, as heroes.

Robert probably gets head trauma shortly after, and forgets most of loop stuff, including Mandy. After his dad was killed out of costume, he gets secretive and moves. She can't manage to get close to Robert Robertson or Mecha Man, and eventually gives up, knowing he'll turn up eventually through some later event.

Phenomaman/Mandy Red String of Fate

A few years later, a red string manifests between Phenomaman and Mandy, drawing them together. When she sees her string going up, she's really hoping it's a super who can control their own flight path, and not a plane that might drag her around. Sure enough, Phenomaman moves much faster than her, and soon lands in front of her, locking the string down to their averaged height.

Phenomaman is a well known superhero, but Mandy's still just a human at this point. He takes her up for a flight, but over the days, it's really impeding his ability to save people. Dragging her everywhere he goes, let alone into dangerous situations, just isn't really an option.

He gifts her the crystal that makes her Blonde Blazer, so they can fly around and fight together. Being tied together isn't great for their mobility, but they do get nicely in sync fighting back to back.

Phenomaman/Robert Bodyswap

Robert gets thrust back into Mandy's life a few years later when he wakes up as Phenomaman. She's Blonde Blazer now, not that he'd really remember her either way. He gets to fly and do everything Phenomaman can, without need for his Mecha suit. He also gets to discover his new alien anatomy 🙃

Katon-Ur is now in this fragile, earth-bound, tiny human body (with new anatomy!). On one hand, he doesn't have the big, masculine frame his people bullied him for, but he also feels uncomfortably vulnerable (and maybe warms up to the familiarity and him-ness of his real body?).

He does borrow the crystal from Blonde Blazer, and Mandy gets to appreciate some time off, where she can just be Mandy. They do try their hand at the Mecha Man suit, Phenomaman can't get the hang of it.

Robert/Courtney Red String of Fate

Courtney's string shows up right after she decides to quit being Invisibitch, and leads her to a hospital, where she finds herself tied to a comatose John Doe. She wasn't sure what she'd find, and didn't feel up for talking about it, so she snuck in, holding her breath whenever staff came to check on him.

After a few uncomfortable hours stuck by his bedside, he had some frantic guests arrive — Blonde Blazer and Phenomaman. Unlike the nurses, they didn't leave, and as she tried to hide behind the bed, his hand must have pulled, Blazer exclaiming he was waking up, before clocking something was wrong. As she was forced to breathe, she looked up at the heroes looming over her.

At first they're suspicious, but despite the string not being visible to other people, it's easy enough to prove by gently tugging his arm from a distance. People knowing is a relief — literally, as she can finally get a bedpan, before they're moved to a more accessible room for her.

She learns who John — a.k.a. Mecha Man a.k.a. Robert is, and Mandy (and Katon-Ur). When she gets sympathy/pity, she responds that it's karma. "I don't know what you think you did to deserve this, but he didn't. Karma didn't do this." (It doesn't help)

Her soulmates (metamours?) come by regularly, bringing food and comfort items and conversation (Phenomaman's stilted and awkward, but it's sweet). When Robert wakes up, she panics and holds her breath. He's still pretty out of it, looking at a string floating in the air, before a girl appears on the end of it.

She helps feed him, and when he's feeling a bit better, takes him on walks with the wheelchair. He's eventually discharged, and she goes with him to Mandy and Katon-Ur's home, meeting Beef, and seeing the pieces of the Mecha Man suit in the corner.

During the months she's been tied to him, she's seen him at his physically weakest, his force of will through physiotherapy and recovery, and then emotionally collapse when he learns the astral pulse is gone, and he can't go back to Mecha Man.

They're finally freed from each other when Robert accepts Mandy's proposal he become a dispatcher, and Courtney agrees to join the Phoenix team.

Blonde Blazer/Invisigal Bodyswap

Mandy gets to experience Courtney's asthma, what it's like to not have your powers freely available whenever you wish, what it's like to run and fight while having to hold your breath. They've all seen her old medical implants, but it's different feeling something hard and artificial embedded in her chest.

Courtney goes from being invisible, to being extra-visible. She always felt like her powers were villain powers, that her destiny was set by them. Now, she's sparkly, and flies, but it's something Blazer chooses to wear, and sometimes chooses not to. Despite their different styles, Invisigal's been part of SDN for a while now, and it really sinks in that she's a hero because of what she chooses to do with her powers, and not because of what they are, or what anyone tells her she is or isn't capable of.

Phenomaman/Invisigal Timeloop

I don't know what they get up to, but this is what it takes for them to finally click. I hope they have more fun with it than Robert and Mandy did 😅

Other quads if you're curious:

Royd/Flambae/Prism/Waterboy