These are the rest of my current sibling or sibling like relationship headcanons, there is bound to be more but as of now these are all
Chilli Pepper + Custard III Sibling like relationship
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These guys, they aren't actual siblings, but they have that kind of relationship. Chilli pepper tends to treat Custard cookie like a little brother, and I can imagine her being very protective of him too. The kind of sibling mentality of "I'm the only one that's allowed to pick on you".
On that same hand I can imagine Custard cookie being a little more friendly with Chilli pepper cookie than the others. Some of the people in the kingdom could probably call Chilli pepper a bad influence on him, which is probably the case but she's nice to him outside of picking on him sometimes.
Espresso + Latte Sibling rivalry
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These two always struck me as siblings since I've seen them. But they also seem like the kind of siblings that don't like eachother. Espresso is mostly cold and latte is a little more kind hearted, and in a dating sense you could say opposites attract, but as siblings I don't really see them getting along.
Even if they don't get along they still have their moments, when they'd be there for one another and help eachother out. They aren't buddies but they don't despise eachother.
Twizzly Gummy + Gumball Different timeline siblings
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Okay, so I'm aware in the main timeline we follow, twizzly gummy doesn't canonically exist. She just jumped times with her group of four. But I think it's possible that Twizzly gummy has a brother waiting for her in her timeline, that being gumball cookie.
Weather twizzly gummy is from the future, which has been theorized, or if she's just from a dystopian Battle ground version of cookie run kingom, I think she still has her own version of gumball cookie there, all that changes is weather he's the older or younger brother.
Angel + Devil One sided care
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I think these guys are siblings similar to espresso and latte. Only difference is that angel cookie actually likes and cares for devil cookie, those feelings just aren't shared.
They bicker and fight about what's right and wrong often, but bottom line angel cookie loves their sibling, and when those feelings are shown through even just a small compliment it makes them happy. Angel cookie thinks there could still be good in devil cookie.
Wind Archer + Sea Fairy Nature siblings
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I pretty much see these two as siblings that are bound by the fact that both water and wind are a part of life, what they could be said to be guardians of. They don't talk often, but they do care for one another. And maybe sea fairy initially watched herb cookie cause he reminded her of the brother she barely ever sees.
Keep in mind these are all headcanons and your allowed to disagree with them.
