The crystal heart is a magnificent artifact. Like the Elements of Harmony, they were not made to destroy, but to expunge.

Not long after his defeat, Sombra returned to the kingdom, not in hostility but humility. The darkness that had taken him was gone. He was the Stallion he had meant to be, the King the Empire had needed long ago.

So does he serve. And in this time...
Somepony of trust became of deep importance to him.

-MXM, SombraxShining Armour, Coltcuddling to the max
-This is just my little guilty pleasure shipping cause i find it oddly cute, even though i know it would never happen, thus the creation of this universe

King Sombra has taken back the Crystal Empire and imprisoned both Shining Armor and Princess Cadence. Any day now, Shining expects word of their scheduled executions. When Sombra comes and asks for a single one of them for retribution, the heroic stallion offers himself without hesitation. Now he only wished he listened to the whole endeavor before volunteering.

(WARNING: May contain words, sentences, and indented paragraphs that may not be to one's liking.)