Why Prince Blueblood can call himself that without committing treason.

[Stainless Steel Fox]

Maybe this would go better in the proposed Lore section, but I'll put it here forst as it's mainly about something in my character's backstory I need to have okayed.

I know the real world explanation, certain TV executives believe American kids are too thick to know what a Duke is, but in universe it's a puzzler. After all, if his aunts are Princesses, he should be a Duke, or Grand Duke at best. Here's my explanation, and the one I'll use in game with the Moods permission. It contradicts nothing in canon as far as I can see.

Between the defeat of Discord and the rise of Nightmare Moon, there was a period where Equestria was broken up into smaller Duchies and Principalities, the Duchy of Canter, comprising Canterlot and it's surrounding towns and villages, being one of them. Even after his defeat, Discord left his mark by having discorded and divided pony-kind.

There is canon evidence for multiple prinicpalities in Equestria at one time in 'Hearts and Hooves Day', where we see in the book with the love potion pictures of an earth pony prince and princess who were going to get married, which suggests two different families forming an alliance. It's also stated that they ruled directly, hence principalities.

The division was not along racial lines, but geographical, and there was none of the hate that drew the Windigoes behind it, but that didn't stop the various tiny nations squabbling like siblings, or rather the Princes and Dukes and Duchesses and so forth doing so. One thing that kept things from getting out of hand were the two alicorns, Celestia and Luna. Not only were they a symbol of all three races combined, they could strut some serious power.

Here's where I have to talk fast. I'm sure the players of the Princesses have their own ideas. My own personal feeling is that they were morttal ponies who ascended, possibly with the help of the Elemenrts of Harmony, to becoming alicorns in order to defeat Discord. Whatever origin you choose, they had to have considered the first Blueblood, Duke of Canter as their cousin. Hence the line ending in our current beloved Duke.

They themselves may have had noble titiles, but they had little or no lands to go with them. Whether there was ever a King and Queen of Equestria is another matter for debate, but the idea is that none of the many nobles would consider letting one of the others declare himself King or Queen of all Equestria, not even one of the alicorns. But the country needed it.

In case your wondering, the upper end generic noble ranks are:

Emperor/Empress

King/Queen

Prince/Princess

Grand Duke/Grand Duchess

Duke/Duchess.

A conclave of nobles decided that the sun and moon could be considered their lands, and gave them a new title Grand Princess, sandwiched in between Queen and Princess. They could accept suzerainty by higher status nobles where they wouldn't accept outright sovereignty by them. The Grand Princesses stayed with their cousin and his descendants, which is where Protector of the Princesses comes from. Remnant vassal states that lasted till the present day are Itaily and Germaney.

Celestia's full title would be Grand Princess of the Sun, and Luna's grand Princess of the Moon. However the term has fallen into disuse as Celestia probably spent the thousand years after banishing Luna in reducing the old duchies and states to mere postal districts. The key point is the difference betwen rank and title. Blueblood's title is Duke, but as his aunts (great) are Grand Princesses, so his rank is one step lower, which also makes him a Prince through his relationship to the Grand Princesses. His mother found this out and pushed him to use it. Mystery solved.