There are a few things that make me doubt how tight this group really is. Perhaps I'm reaching, but this is what I got:
1. Cole is always shown to be the offender.
2. When the kids tried to escape HERO, they were split. Shen and Briar had already left, while Zara seemed to get into trouble and Cole went back to save her. Perhaps that was part of their tactic, but I'd expect a group that has been together for years to stick together and have each other's backs.
3. Shen in the previous update seemed very bitter about how Cole treated him in the past. This isn't the emotion I'd expect to see in a "sibling rivarly" type of relationship. Anger, dickmeasuring, outrageous threats, sure. But bitterness? This generally points to abuse.
4. The kids are in a very tight spot. Ella is dead and can't guide them and they try to follow her steps and whatever instructions she has given them while hoping that if they do, she will come back to them. Shen actually mentions that holding MC captive may somehow cause Ella to come back to them faster. Cole constantly messes with that status quo by trying to be "the one". If I had to guess who the kids like more between Cole and Ella, I think Ella is the obvious answer. In a sense, Cole taking such a beating could even be advantageous to them in the long run. The kids know that Ella wants to give "everything" to her chosen (it may be true, it may be not, but that's what they know). Taking MC away from her could put her whole plan in jeopardy as far as they know.
And yes you are correct, Stockholm Syndrome refers to kidnappings which is why I said "kinda". After all Cole acts like the leader of that group and since the outsiders identify them as such, his actions reflect on all of them, so I thought about it as him holding their existences captive in a sense.
No definitely Cole isn't anybody's favorite person even within their group, Zara is the only person on the planet that wants to bang him and even she seems to understand he isn't a very likable person. Cole and Shen definitely have a hate-bonner for each other as they compete for the role of "big bro" of the group. While Briar seems very passive and non-combative in the whole thing.
Yet going through the troublesome childhood that they did there seems to have formed a deep bond between the group. Despite Shen and Cole repeatedly arguing amongst themselves and with Cole trying to impose his dominance over Shen and the others. With Shen and Cole both talking about their Evolution Levels and powers against each other there are no instances of them ever openly fighting against each other like there is between Cole and Charlie.
I guess I'd say the group is a strange mix, being on the verge of collapse because their growth is so stunted. Even with their minds aging and their bodies evolving none of them really behave like grown men but instead are quite childish and brash.
It might also largely be because of Ella, they wouldn't dare fight amongst themselves and actually hurt someone in the group cause they can't bare the thought of how ashamed they would feel when Big Sis found out about it ? Even after her death most of them seem to believe she will be back. They are as a group devoted to her.
Even Cole is his usual MEGA douche self to her during their first few meetings as children but eventually ends up opening simping to her while still being an asshole.
2. When the kids tried to escape HERO, they were split. Shen and Briar had already left, while Zara seemed to get into trouble and Cole went back to save her. Perhaps that was part of their tactic, but I'd expect a group that has been together for years to stick together and have each other's backs.
I am not saying they preplanned this but usually whenever there is any prison break type scenario and a group of inmates escape their captors they usually split up almost instantly after getting out to make themselves harder to track and improve the chances of most of them escaping even if one or two of them do get chased down and recaptured.
Them escaping in groups of 2's is kinda weird maybe it was just how Circumstances allowed them to escape ? Maybe Shen was in-charge of Briar while Cole was in-charge of Zara ? Maybe they were supposed to make sure their charges made it out with them ? Or maybe in their usual retarded fashion instead of properly planning Cole and Shen just had a dumbass moment and ended up fighting and splitting up cause neither of them wanted to follow the other's lead and while Shen dragged Briar away with him Zara got in trouble cause she couldn't decisively chose between them who to follow ? This is all speculation btw.
3. Shen in the previous update seemed very bitter about how Cole treated him in the past. This isn't the emotion I'd expect to see in a "sibling rivarly" type of relationship. Anger, dickmeasuring, outrageous threats, sure. But bitterness? This generally points to abuse.
Shen's bitterness would make sense since Unlike Cole Shen's nature doesn't seem to allow him to openly be an asshole like Cole... while Cole has the release of just being an obnoxious cunt, Shen has to actually try to behave like an adult which would cause him to harbor feelings of resentment which would fester into bitterness since he cannot release them in any healthy manner. Probably best way for Shen to release them would be for him to either also start behaving like Cole which he doesn't seem to want to do. Or to actually do what the MC did and punch Cole in his fucking mouth really fucking hard. which again would probably not something Big Sis would look upon very favorably ...
Hence why Shen probably feels trapped in his role in the group, He can't just leave them and Cole does nothing to help make things easy for him so he does have bitterness or resentment inside him.
When Shen saw MC standing over Cole as Cole lay there coughing up blood while MC picked his teeth out of his fist Shen probably secretly felt jealous too but he still couldn't let MC kill Cole cause Shen still wants to be a candidate for Big Bro of the group at-least till Big Sis gets back.
I guarantee he Secretly feels things would be better if Cole just left or suddenly decided to become quiet and obedient.
TL;DR : it's a complicated Love+Hate relationship, they are a weird family that is on the verge of chocking or fucking each other
inbetween yelling at Briar to Speak UP cause nobody can hear him mumbling. Half of them wanna kill each other but can't cause they would look bad to the others.