Just so I understand correctly, you want to be able to assign a specific portrait to a player regardless of what they actually look like? If so, there may be a way to pull this off with the respec version of character creation and inserting a visual asset of the desired portrait in between the line of sight of the icon generation camera and the character teleportation trigger used during the respec process.
Proof of concept with everyone's favorite painting from Origins

![[Linked Image]](https://i.imgur.com/DtGeKMJ.png)
![[Linked Image]](https://i.imgur.com/P0rTmsu.png)