I was working on the alternate timeline story, where things happens slightly differently. ( Sunset Shimmer remain Celestia's the main student, Twilight is Celestia's the second student, Fluttershy stays hermit, Rainbow Dash never came to Ponyville. )
A one particular idea cross to my mind: What if Prince Blueblood was dating Princess Cadence?

*Imagine the fandom's reaction*

Yeah, the idea doesn't sound quite attractive. ( Especially as fellow Shining Armor & Cadence's fan myself. )
However it isn't impossible. Since Cadenze & Blueblood aren't related. I assume that they both are adopted.

Broken hearted Shining Armor goes to Ponyville to hang out with his sister and Spike, as he tries to bounce back from the break-up with Cadence and ends up becoming the element of loyalty.

6421016
Except if weren't dating in the first place?
( While I was planning in my story to make them couple in "Best Night Ever" chapter. Just like with Spike x Rarity relationship, except it's going to be complicated since Spike has feelings on someone else in that timeline. )

After the fiasco which was the Royal Wedding, Chrysalis was forced to resort to Plan B; B for Blueblood.

6421148
I wonder if the Changeling invasion could happen much sooner. At "The Best Night Ever" episode I mean. Having infiltrate into the gala, among the nobles and launch the night attack.

6421156
Rarity competes against Cadance Chrysalis for Blueblood's love.

6421159
Chrysalis x Blueblood....That's sound an interesting concept.

Its sounds like a good story. One aspect I had originally planned for my Assassins and Tyrant story line was that Cadance acted like a medium for ponies to fall in love with her and then she slowly eased said pony into following in love with another pony. In some ways I plan to do that but with NMM and twilight. She would have done the same with others. I feel like she being the princess of love she could get away with passing lovers by her until she could find one of her own.

6422072
Well I was thinking her being bi-sexual in my story.
Noticing Gilda being into a mares and she don't mind if she likes to sleep with her. ( or sharing Prince Blueblood with Gilda. )

'Damn, you're a kinky girl, Cadence!'