The Little's By Themselves
If Ponyboy is completely by himself when he regresses; initially he's confused and scared but when he realizes he's alone, he quietly sits in his room and plays. He'll usually also get a cup of water and his sippy cup from the fridge since he knows that every morning a cup of soda prepared just in case Pony slips during the day and Two-Bit's around, since Two-Bit will give Pony regular pepsi instead of water'd down Pepsi.
Most times he's alone for upwards to an hour before he'll lay down, the glass of water on the floor and his sippy cup in his arms when he curls up in bed and falls asleep, dressed in Sodapop's flannel and Darry's sweatpants and his thumb in his mouth.
When the gang gets to the household, it's Sodapop who finds him after noticing a slight mess in the kitchen (and picking it up before Darry saw it) and goes to find Ponyboy, and immediately runs to get Darry to show him. They gently wake him up because there is no doubt that Pony's thumb hurts, and they replace it with a pacifier when Pony is barely processing who's waking him up. They let him go back to sleep for a little bit longer, wanting to have food ready at the very least before they wake him up, since most of the times Pony's in trouble, it's because he was woken up and not given something.
Sodapop also picks up the cup off the ground before Darry processes that it's there and they take the sippy cup to set on the night stand, though Darry also fills it up (still watered down) as a 'surprise' of sorts. Sometimes Johnny joins him, also dressed in Soda's and Darry's clothes.
Darry and Soda have the most comfortable clothes.
If Johnny is completely by himself when he regresses, he'll normally get really anxious and cry. Sometimes he'll cry himself to sleep, sucking his thumb and curled up in a ball clutching his jacket. Sometimes, if he's small enough, he'll make his way to Pony and Soda's room and change into Pony's clothes and have one of Soda's flannels and curl up and fall asleep, still having cried himself to sleep because he really really doesn't like being alone.
Most times, he wakes up still regressed with Ponyboy curled up beside him. Sometimes it'll be Sodapop on the bed with Johnny (and sometimes Johnny and Pony), sometimes he'll wake up with Dally gently shaking him and Dally will carry and hold him. Sometimes it's Darry or Two-Bit. Everyone always replaces his thumb with a pacifier and gives him a stuffed animal and they sit with him until Johnny perks up and goes to join Ponyboy.
If Pony and Johnny are together when they regress, the two of them play in the living room, albeit more careful than they normally would, since if they get hurt, they are alone and can't get anyone to help unless one of them un-regressed. If they are alone for more than an hour, the two will get bored enough and will end up in Pony and Soda's room to nap, since Pony does not like the couch for some reason.
They'll change clothes, with Johnny having to direct them (with Johnny being 'older' than Pony) and they'll curl up in bed giggling together. They always have sippy cups with them and Johnny even cuddles with a stuffed animal that was gotten specifically for him.
They'll fall asleep with thumbs in their mouths, or partially in Johnny's case, until they are found by one of the gang, who gently baby them awake, being careful when it comes to Pony, and pacifiers are given to the littles.
If Sodapop is by himself and he regresses, he is usually taken off guard and he cries a little before making a huge mess. He never goes into the kitchen as it scares the hell out of him. He'll also probably end up a little hurt. He'll always be spooked when someone from the gang comes home. He always ends up in some sort of trouble with Darry because of the mess, and he'll get sort of fussed over because he's always a little hurt.
Sometimes his knees will be hurting him and so he's sort of crying and fussy when Darry's dealing out a punishment, which cuts the punishment short because Sodapop absolutely not tell someone when he's hurt when he's in trouble because it's a form of self punishment (honey, if you do this, please don't, don't let yourself hurt just because you are in trouble).
If Dally is by himself and he regresses, it depends on where he is. If he's at Buck's, Buck will come across Little Dal and call Darry and say that "Dally's actin' weird and Buck didn't want to 'deal with it'."
If he's at the Curtis house already, he'll curl up by himself either on the couch or in Darry's chair and just wait. He's too scared to do anything else, and sometimes he'll fall asleep and other times he'll manage to stay awake until the gang gets back.
Two-Bit always jumps at taking care of Dally if Darry's actually too tired to, or Darry will take care of Dally, after making sure that Dally is okay, since Dally regresses slightly less than Sodapop.
(The two, Dally and Soda, regress in a 'schedule' of sorts, never more than a certain number of days per week and only occasionally at the same time)
If Soda and Dally are together when they regress they fight really badly. Little Soda does not like Little Dal, and Little Dal likes to spite Little Soda. When the gang gets back, punishments do have to be dealt out because both of them are in tears and both are hurt to some degree.
They'd be separated and taken care of before punishments were dealt out to the both of them. They'd be kept apart for the rest of the night, and for additional punishment, neither could see Pony or Johnny or help with them or cuddle with them. That worked better than any other punishment for Little Soda and Little Dal, which was noted on the punishment chart that Darry had made.
If Soda and Pony are together when they regress, they like to be a little mischievousness when it's just them. Pony will sneak into the kitchen, with Soda joining him because while the kitchen scares Soda, he isn't scared when Pony's there, or it's possible that Soda just wants to protect Pony. They'll get a couple snacks, with Pony being wide eyed when Soda found the candy stash (that belonged to them anyways, but to Little Pony and Little Soda, it wasn't theirs in their mind).
And the two of them curl up on the couch snacking on a little candy, a bag of chips, and drinking from sippy cups. Sometimes Ponyboy will fall asleep, and Sodapop will make sure he has a pacifier before Ponyboy actually falls asleep. Sometimes Sodapop will also fall asleep until the gang gets back.
If Soda and Johnny are together when they regress, it's always cuddle time for them. They'll curl up on the couch, Johnny with a pacifier and stuffed animal and freshly changed into some of Sodapop's or Ponyboy's clothes, and Sodapop changed into pajamas and a stuffed animal. They both refuse to go near the kitchen, so no sippy cups for them this time. When the gang comes home, Ponyboy usually gets their sippy cups for them and either attempts homework or immediately regresses with them. And with there, the fourth is never long after.
It's a bit rarer, but if Dally and Pony are together when they regress the two of them play, though they are pretty quiet. Little Dal is pretty quiet, and usually younger than Pony, Johnny, or Soda; and Little Pony is normally non-verbal anyways, so they just play quietly together if they aren't coloring. Ponyboy keeps them out of trouble by making sure that Dal doesn't draw on anything that's the paper.
Sodapop is more than happy to color and cuddle with them when they gang finds them, and Little Dal is more than happy to capitalize on that. Pony's content with Johnny or Two-Bit most times anyways.
If Dally and Johnny are together when they regress it's immediate cuddles and nap time. Though if they are at Buck's, Buck will call the Curtis household for someone to come get them. Normally it's Two-Bit because Darry's at work, but if it's late enough, Darry will come get them.
If they are at the Curtis house already, they curl up on the couch, or sometimes on the floor in front of the couch, and cuddle for nap time. Though Dally will get their sippy cups from the fridge before hand, pacifier's, and then they curl up.
The gang coo over them and always make sure to be way quieter than normal when they come home to find the sight.
If the four are together and they all regress, rare but it has happened, it's usually chaos. Soda and Dal always find something to bicker or fight about, and it usually stresses Pony and Johnny right out and makes them regress younger, and sometimes they'll cry. But most times Pony and Soda play together with building blocks or toy cars or something, while Johnny and Dally color or cuddle for a while.
Little Pony and Little Johnny just try keep Little Soda and Little Dal's interactions to an absolute minimum out of fear of how the two will mix and interact, especially with no cargivers around to stop anything from going too far.
At some point, they also all curl up for nap time together, with Little Soda and Little Dal coming to an unspoken truce for Little Pony and Little Johnny. Sippy's, Pacifier's, and changes of clothes (with Soda guiding Pony and Johnny) and they all curl up somewhere, usually in Darry's room. It always scares the gang when they come home to see obvious remnants of their being littles active but no littles. Every time.