The Holy Sword Wielder from the Other Side of the Diorama

The knight king, who thought little of himself, never imagined that anyone could truly love him.

Then a brown-haired boy appeared before him, tore open his chest, pulled out his heart, and showed him everything.

The knight king felt tears slide down his face.

We met a long time ago. I've been watching you, always, always.

The boy said this.

The lonely courtyard finally welcomed its first guest: the ancient king of Britain.

Those five minutes were the only comfort the monster in the courtyard had.

But one day, the king died, and the monster went mad.

The beast with seven heads and ten horns bowed before the world's will:

Grant me a new identity.

I... would do anything for his sake.

Please note:

1. The pairing is Anting from A Certain Magical Index x Fate's Saber Alter.

2. The only one who sees the dragon at the beginning and the end is Saber Alter. There is no Commander.

3. I've rearranged some elements from A Certain Magical Index and placed them in different locations.

4. The Knights and Merlin don't know Saber Alter, and there are various other headcanons.

5. The blurb and title are provisional. Feel free to suggest something better.

Theme: There is surely someone in this world who loves you deeply