Hi! Yes I would be happy too! My concept that I was going off of was how the reef na’vi have spirit sisters and brothers, aka, their tulkun. I wanted to create something in my story that is just as a special bond that is shared between tulkun and reef na’vi but on land. The idea of a soul sister is a deep bond between two people. They don't have to be related for this to happen. Essentially, soul sisters are something that I have made to be very rare upon the na’vi. Their connection runs so deep that it's not even breakable through death. (similar to how an ikran is loyal to only one rider throughout all its life, even if their rider has died). A soul sister is fiercely protective over the other person, they can feel what the other person feels etc. They are pretty much there for the other person through thick and thin, and are their to advise them along the way. Pretty much they are platonic soulmates, that can feel what the other is feeling through a bond that is created without having to use tsaheylu. I hope this helps and if you have any more questions please feel free to ask away.