Random thing because for some reason I ended up here. Messia wore a slave collar. Some slaves did have their collars removed but most were designed for permanent wear. And yet in that scene ☝️ she wasn't wearing one. Far as I've read, and FYI I'm no historian, I just know random bits and look up others. Plus hardly anything about this What If was accurate. Anyway....
Types of collars were: Riveted/Soldered. These were designed to be impossible to remove without tools. Usually for slaves with a high likelihood of running away. Then the removable ones which had bolts or locking mechanisms.
Reasons they'd be removed: A worn or broken collar could be removed to be replaced, after escape some are found when the slave has gotten away successfully, and when their master decides to free them.
While specialized, riveted collars, often had inscriptions like "tene me et revoca me" (hold me and return me) were usually permanent punishment for runaways, other types were less severe, and some found discarded, indicating they could be removed. So, either this was just for the moment, for theatrics since it was back on when they were leaving, or, random thought, Messia might be technically free since Cornelia would have had it removed and has her now. Who knows?
Also I did edit that image cause I used it for a head canon for my Druid about giants milk. Randomness continues