Maybe I'm just one for the dramatics, but I don't really see people talking and really acknowledging how Ponyboy literally almost died that night in the fountain. Like, if they'd pushed his head under a bit too far he would've cracked his head open, and even though they didn't, he quite literally lost consciousness. He'd gone limp when Johnny stabbed Bob. If his body hadn't automatically coughed up that water he'd be dead, considering CPR wasn't something I imagine Johnny would know or think about doing. Ponyboy was being drowned to death and almost died. Like, I feel as though we just don't focus on how Pony was quite literally on the verge of death. So here are some headcanons of how the gang would react upon hearing that Pony almost drowned.
Johnny already knew. He didn't just stab Bob because he was torturing Pony and would go after Johnny next, he stabbed Bob because he was killing Pony. That's why he was so protective and emphasized Pony's age in that one scene (it's my fault for bringing a 14 year old kid along. that one) - because if he hadn't stabbed Bob, Pony would be dead. In fact, I think that before everything with Bob happened, Johnny had never before been outwardly protective of Pony or treated him like he was younger or anything like that. After all, Pony said that Johnny just understands him and gets him without needing to say a word, and with how defensive Pony is about fitting in and not being a baby and such, I can't imagine he would've said that if Johnny had shown a tendency to think of Pony as a kid. Maybe Johnny was secretly protective, but he definitely didn't show it until the fountain, and until he felt the weight of Pony's life in his hands. (and yes, Johnny not wanting to get jumped was a part of the reason he killed Bob, but lets be real - the boy was actively suicidal and watching his best friend get killed right in from of him, Pony was probably at the forefront of his mind at the moment, the way Johnny was Pony's last thought before passing out)
They didn't tell Dally what happened when they went to him for help, but he figured it out after they escaped and he got some sleep. Johnny wouldn't kill someone unless he really thought they would severely hurt him or Pony, the way they did when they jumped him before, but he didn't seem too beat-up. Meanwhile, Pony was soaking wet from his hair to his waist and crying, and Bob Sheldon is revealed to have been stabbed directly over the fountain. Pony also probably sounded different from all the strain drowning put on his throat and lungs. It doesn't take a genius once you put the pieces together. Dally was pissed about it. He almost jumped Cherry when he next saw her (page 93), and went on a rampage around Tulsa beating on anyone who looked at him wrong. If Bob was buried before Dally went to go check on Johnny and Pony, then Dally went to his grave and spat on it or something. Randy probably was in hiding that week due to grief and shame, but Dally got his hands on the rest of Bob's close circle of friends. When Dally dies, some of his last thoughts are about the gang, and especially Ponyboy. He knows the kid could never bring himself to toughen up, and now Dally won't be here to protect him anymore and he wasted his last words on telling the most kind kid he knows to not be kind anymore. It's his final and biggest regret, along with leaving the gang.
The rest of the gang didn't find out until the hearing, and didn't hear Pony's side until after he wrote The Outsiders.
Darry was fucking distraught. If Bob wasn't already dead, Darry (and Soda) would kill him himself. He wouldn't let Pony go out without Darry or a member of that gang being with him, and the fear that Pony could've drowned made Darry develop a fear of Pony being around water. The park? Absolutely not. Too-long showers? Darry's knocking and making sure Pony is alive before he yells about the bill. Fishing trip? Fuck no. Darry lived the rest of his life with the guilt that if he just hadn't hit Pony, Pony would've never gotten drowned and Johnny and Dally would've lived. He also thinks about his potential last words to Pony. He has nightmares where that night goes as it did in real life, but Pony is killed at the fountain and Darry never gets a chance to apologize or clear the air with his brother.
Soda was also distraught. He felt like if he'd just diffused Darry and Pony's argument better, before things got out of hand, his baby brother wouldn't have had to go through that. Any time Ponyboy so much as takes a sigh after a sip of water, Soda is having terrible images of Pony never catching his breath again. He (and Darry) cries about it when Pony is out. Soda hates the park now, he just can't stand it. And any time he sees a fountain or a Soc that used to run with Bob, he's scowling and ready to fight with the next person who so much as pokes him.
Steve doesn't stop thinking about what could've been his last words to Pony because really, he doesn't remember them. He knows he always treated Johnny with his own version of kindness (not that he doesn't wish he couldn't have said goodbye), and that he did what he could for Dally (again, doesn't make it any less devastating), but what did he last say to Pony before that night at the fountain? At least with Johnny and Dally, he can comfort himself by saying he was there for them, and he knows that they knew he cared, but could he say the same thing for Pony? He gives the kid free pepsi and is kind to him, but never outwardly. Never to his face. Never in a way the kid could understand. If he'd died at the fountain, would he have died thinking Steve never cared? Steve is very careful with Pony after that, and his last words to anyone in the gang before they part are always something nice or playful.
Two-Bit drinks. A lot. Sometimes he thinks of literally drowning himself in alcohol to feel how Pony felt. He does a lot of drunken crying at bars, on street corners, and at home when his mom and sister aren't around. He attends school more often, but only to follow Pony around and hang outside his classroom door so he knows Pony is okay. Like Soda, the image of Pony drowning haunts him, so he watches Pony very closely when he's around water. Two-Bit feels that if he'd just made sure that the kids had gotten back to the Curtis house, instead of leaving them to take care of themselves, it would've never happened, and he blames himself a lot for that. For wanting to play pool and poker and get drunk, instead of making sure his friends were okay. He also thinks a lot about his words to Pony that night- saying he would smack him if Pony wasn't Soda and Darry's brother, telling him that Pony would never defend himself with the bottle Two-Bit gave him. If Pony'd drowned that night, those would be some of his last meaningful words to the kid.