How do conjoined fabrials interact with speed bubbles?

[Tarmogoyf]

https://wob.coppermind.net/events/105/#e1150

I saw this WoB about a spear being thrown through a speed bubble, and Brandon said the spear would be either in or out of the speed bubble, based on how it views itself. How do conjoined fabrials view themselves and does that affect their interactions with speed bubbles? For example, if you have a spanreed inside a speed bubble, and its paired spanreed outside, do they view themselves as one thing, and if so will they both be counted as inside or outside? 

Edited December 30, 2021 by Tarmogoyf

[Ixthos]

I suspect their movements would remain in sync but they would individually experience different passages of time, and so trying to move one on the inside of a bubble would produce a movement of the one on the outside that perfectly matches it, but with greater or lesser force, depending. So a Slider trying to move one in a bubble of sped-up time would find it heaver due to the drag on it, and an outside observer would see it moving very quickly, while a Pulser would find it lighter and the outside object would move more slowly to an outside observer. Basically like with gears, you gain greater speed for less torque or vice versa.