Breath interacting with a person in all 3 realms.

[TheWanderer he/him]

Intro
I have returned for yet another attempt to theorize and understand one of the many magics of the Cosmere. This time I am tackling breath, one of my favorite magic systems, though I do love them all. As many of you undoubtedly know, everybody's favorite wanderer has shown us a less than well known use for breath. While there was prior evidence of breath being tied to memory from two scenes in Warbreaker (the little girl, and the offer to Denth) this aspect has yet to be explored or explained much. I apologize in advance if their is a WOB that already talks about this, I keep forgetting to read them all.
Some Background
In very typical fashion for me, I felt compelled to try and understand this more. So I turned to the wonderful coppermind and Warbreaker itself. In it I found a most peculiar note, "If enough Breaths are collected, they can start to affect the personality of the person holding them. "Breaths do bring some things along with them,", but they are not "terribly individual" depending on their original owner. For example, Vahr's resolve was strengthened because of the similar mindsets of those he collected his Breaths from, but the effect only manifested due to the large amount of Breaths he had." 
The Theory one: How Breath Connects To The Bearer
Now given textual evidence and assuming this is accurate I propose. Breath actually has an impact on a person in all 3 realms to a greater extent than the average magic system (which to me makes sense for Endowment). Though one could argue it is simply because one can acquire more of it more easily than most other Cosmere magic systems. The physical is easily seen, as many of the heightenings provide benefits that are at least tangentially physical (and arguably cognitive). As for the cognitive aspect, I think that like a cognitive shadow, breaths imprint slightly upon a person's spirit web and or their cognitive aspect. Hence how they can influence a person's personality if they collect a lot of it. However, due to the relatively small amount of investiture per breath this effect is greatly diminished. Likely only picking up a modicum of a person's thoughts and feelings that is only noticeable if those you get the breath from have a similar mindset. Finally, there is the spiritual aspect to consider. While there is really only one concrete example I think Susebron gives us some idea what this entails. Although he is no sliver, the sheer quantity of investiture bound to him would in my eyes on some level expand his soul in a similar if lesser manner. Given we do not know as much about the greater levels of heightening I sadly cannot back this up with much evidence. Though I do believe the way in which the more breath you have makes you better at awakening when you first begin might tie into a spiritual connection with endowment and awakening as a magic system. Yet, I could see an argument for this being a cognitive not spiritual effect. 
Theory two: How This Connects To Memory
Now assuming I am at least on the right track. Then the question is, how does this allow you to store memories in them? I would propose given the ties to multiple aspects of a person (particularly cognitive and spiritual) there is a way to exploit this to impact memory. When Vasher tells the little girl to speak a certain command, Vivenna notices her breath flickers. To me this implies a portion of the breath and the cognitive tie to that memory have been severed from the girl. As for Hoid using it as a memory storage, once again. Given the impact memory can have on your cognitive aspect, and how are memories shape our identity. It does not feel like a great leap in logic to assume that one could use those breaths to store those memories. As the breaths in question are tied to a person in just about every way. Though whether using them to awaken or storing the breaths in something like clothes would degrade or destroy the memories I do not know. Granted I imagine it requires a great knowledge of investiture to do this, but many things are possible with the right application of knowledge. 
Afterword
Just wanted to say thanks for reading everyone. Happy to discuss further if you feel so inclined. Sorry if my thought process is hard to follow or I seem to be making too great a leap in logic. Also hope people like the new format I am using for my theories. Feel like it helps make them more digestible and easy to follow. 

Edited April 7, 2021 by TheWanderer

[LewsTherinTelescope]

4 hours ago, TheWanderer said:

Breath actually has an impact on a person in all 3 realms to a greater extent than the average magic system (which to me makes sense for Endowment). Though one could argue it is simply because one can acquire more of it more easily than most other Cosmere magic systems.

I don't really agree, we see Stormlight have some pretty large effects on people as well (improving their physical capability, driving them to act, even healing them). I think it's the other argument that you present, it's just easier to acquire larger amounts of Investiture via Breath than, say, Allomancy.

Edited April 7, 2021 by LewsTherinTelescope
remove redundant words that were repeated

[TheWanderer he/him]

I an concede that to a point, but stormlight burns quickly and leaves the body just as fast. Whereas Breath is something that remains with you for extended periods (assuming you don't hide or use it). Either way, I by no means expect to get things completely right and appreciate your engagement with the idea.

[Honorless he/him]

21 hours ago, TheWanderer said:

spiritual connection with endowment and awakening as a magic system

That's an interesting phrasing and something I never really thought about! Are you suggesting the Invested Arts would be a discrete object in the Spiritual Realm and not just a pattern that tends to arise via interaction between the Spiritwebs of the magic users, Investiture from the Shard(s) and the Shardworld(s)?

Oh, and here's an older topic you might find interesting:

Good point on BioChromatic Breath remaining with the person for a long time, compared to Investiture like the Lights (usually)  or the Investiture tapped from metals in Allomancy. Hmm... Magics from the Dor seem to fall in both categories, Elantrians are suffused with Investiture, as are Dakhor, but not Forgers. Hemalurgy can let you specifically target someone's mental fortitude but does stealing a lot of attributes from the same or similar person affect a Hemalurgist? Plus, they get holes in their Spiritweb & Cognition. Huh, wonder how Feruchemy falls into this.

Edited April 8, 2021 by Honorless

[TheWanderer he/him]

"That's an interesting phrasing and something I never really thought about! Are you suggesting the Invested Arts would be a discrete object in the Spiritual Realm and not just a pattern that tends to arise via interaction between the Spiritwebs of the magic users, Investiture from the Shard(s) and the Shardworld(s)?

Oh, and here's an older topic you might find interesting:"
Well yes and no, I know shards exist in all 3 realms and that the magics of a planet are based upon that shard' interacting with it. So to me greater connection to a shard would likely increase connection to the magic as well. Essentially, I think the shard may have its greatest presence in the spiritual realm. Given that their perpendicularity is the only physical (aside from Scadrial), and we never see shards in the cognitive realm aside from cognitive shadows. Thus they have to reside somewhere more and induction leads me to believe that is the spiritual realm. Of course I may be wrong, and I like where your mind is going. I simply think that Breath given endowments particular nature forges a greater connection. Granted for more genetic magic systems this might not apply. Breath is unique in that it is one of the only magic systems involving hoarding the magic fuel, and that caveat of the more you have the better you are at it. Also I am now wondering if a similar mindset could be applied to the oaths as you progress on Roshar.

Edited April 8, 2021 by TheWanderer