Can we have a little bit of insight into Spike and Cyan’s relationship? I feel like we never really seen them interacting, even thought it would be interesting with the fact that they are both prideful and wary of new people
Huh, I haven't, have I? Sure, it'll be fun to think about.
Admittedly, of the combos of Kais and Nyas, their relationship is the most strained, but only comparatively. They still like each other and see each other as another sibling, but can clash a bit on how they treat each other. It comes from their vastly different dynamics with their own sibling.
Buddy Kai and Cyan Nya are twins. Cyan is only younger by five minutes. Buddy is still protective of her because he's a Kai and they tend to do that, but their relationship growing up has always been as equals with a stable home life that allowed them to grow and mature at their own pace.
Then we have Spike Kai and Red Nya. There is an age gap of at least a few years between Spike and Red, and with their parents disappearing when Red was, like, 3, Spike had to step up and be the parent, forcing him to grow up too fast, and assert his big brother authority as much as he could over someone as independent as Red. They love each other, but Spike is undeniably the 'big brother'.
And in this comes the clash. In Spike Kai's mind, Cyan Nya is a Nya, and therefore, his little sister, whom he needs to protect and care for. But Cyan, who has established herself as 'big sis Nya' in her friend group (regardless of actual age, and mostly to Luh-Loyd but also to others when needed), refuses to be 'little sistered' by a version of someone she has always seen as an equal. It doesn't come out often, but if Spike ever hints at talking down to or presuming authority over Cyan, she shuts that down immediately. It never goes far, and over time, Spike sees Cyan as her own person and his second sister rather than just an extension of his Nya. Meanwhile, Cyan, after recognizing her unwillingness to ask for help was the block to her true potential, allows herself to be vulnerable around him and let him 'big brother' her from time to time.
Also we do see a bit of bonding between them in the beginning of Chapter 10 of Trials of Trust- Link
