He could be either Prince or Commander, depending on which role he’s acting in at a given time (like how the President is also the Commander in Chief).

@NavelColt  
Them being a communial family actually makes quite a bit of sense, especially when he hasn’t been called a Prince or King.

@DarkObsidian  
Interestingly enough, the drones have referred to Thorax by his first name only, so far - the one time ‘leader’ was used was when a drone was reminding him of his role, not so much using a title before his name.
 
I think it’s predominantly a communal family hierarchy too, with Thorax technically still being the ‘king’ of the hive, and Pharynx being a ‘prince’. The world probably sees Thorax and Pharynx as those things, but among the changelings I think titles aren’t quite so important, not anymore.
 
I’ve explored this a bit in fan fiction quite a bit, as too have I been seeing it elsewhere. :) One thing everyone seems to agree on is that Thorax’s modern rule of the hive is far more like a working family than it is a traditional monarchy. I think it fits Thorax perfectly, even as a leader he’s still caring for his family and friends he never got to appreciate, before.

@Depressed Knoll
 
You mean like Queen Novo? Yeah, that could work. And yeah, considering the different types of bodies it is reasonable. Still I’m stick with the communal family. All new changelings are hippies! Peace, Love, Harmony! They should invite Treehugger to live with them. :-D
 
It’s spring time for Pharynx in Equestria…

@DarkObsidian  
Seeing as the show as a good queen, Thorax being king isn’t far fetched. And seeing as how Thorax and Pharynx’s bodies are different from all the other changelings, I think it’s safe to say that it’s still the system or royals and drones.

@Depressed Knoll
 
I’m just confused. Actually Thorax wasn’t titled “king” in the show ever . They always called him “leader”. And considering the social life in the new hive in “To Change a Changeling” I’m pretty sure they don’t live in a monarchy anymore. More like in a communal family. Isn’t the term king not the same thing like queen? Only used for villians? ;-D
 
I don’t have a problem with this, I never heard it before, so, okay, why not? Let’s ignore the consistency problem. ;-)

Seems like it is spring in bug country.. :)

@DarkObsidian  
Since his brother is king, he is a prince, though he can also be a guard.

Pharynx is a prince now? Well, why not. I thought he would be the commander of the guards. Maybe both now. They still HAVE guards, riiggghhhhttttt…?
 
Augen wieder geradeaus! Sir, yes, Sir. :-D