So I have been doing research for the wiki on the Ryshadium, Sureblood and Gallant. And as I have been looking back through Oathbringer I have noticed some interesting development and a lot of glaring gaps when it comes to the Ryshadium, specifically the way they choose a rider.
Every time in every book when taming the Ryshadium or being chosen by a Ryshadium is brought up it is vague or cut off in the characters thoughts. I am starting to think this is on purpose. We know that you must be chosen by a Ryshadium otherwise they cannot be tamed, we don't know anything about this process.
Additionally there is some interesting development with Dalinar in relation to horses in the flashbacks of Oathbringer. At the beginning he rides a horse and doesn't care at all when he breaks it's back in battle, compared to now when he has this special connection with Gallant. For me that shows a lot of development in a lot of ways. He went from a man who would never be chosen by a Ryshadium, to one who was chosen.
Also does anyone have any theories as to why music spren would be seen around Ryshadium? Are there any book descriptions of music spren?