SpookyDood made a video comparing Goners to the dead, people who were around but are now forgotten. The word goner in itself is slang for someone being dead. 

https://m.youtube.com/watch?v=mbtGDvZ8V2M

HalfBreadChaos also made a video comparing Kris to a Zombie, with allisona comparing Kris to a Zombie or a corpse 

https://m.youtube.com/watch?v=YImYE3SDMkY&t=69s


So, I thought to myself what if these Ideaa are connected. Another common theory is someone drowned in the ocean at some point due to the dark world's water allison and naming scheme. I am suggesting that the one that drowned was Kris, in fact Kris' Dark World color scheme arguably looks like a drowned body. After Kris' body drowned however their body was retrieved by Gaster, using it as the bases of a new goner to control. This is when the goner sequence begins, however instead Kris refused to to die. Kris was able to persist thanks to their determination. However now that we are connected to their body after the goner sequence, Kris' autonomy is reduced. In this scenario we aren't directly controlling Kris, rather the Goner body Kris' was made into, and Kris is struggling to keep themselves alive and in control. The only way we would get full control of Kris is if their body dies.

As for Kris' colors not matching a goner, we have seen with Clam girl a goner's colors can switch between monochrome and colored. I suggest a similar phenomenon is happening to Kris. 

Well that's my little last minute theory time capsule, though if I am honest not much of a theory it's more of a hypothesis. Regardless I felt I needed to get it out somehow before the release of chapter 3 & 4.

My Kris Goner hypothesis (Last Minute Theory)