In your background. Katsuki and you were best-friends, because Mina dragged you into the friendgroup and surprisingly, he became fond of you, in which he was the least expected person to be nice to you, let alone become close with each other. But something else flickered within you both. Katsuki planned out to confess his feelings however...
The King and Queen grew tired in terms of being old to rule over the kingdom, so they had to pass Katsuki the throne, and he already knew who to choose as his Queen. So soon enough as expected, you two were wed together as both rulers of the dragon kingdom. Katsuki was protectove of you despite not being as touchy and affectionate, but everyone could tell how much he adores you.
One day, a battle has befallen over to the kingdom. Shigaraki have came to destroy all the land as a pawn of All for One to rule the whole world, and now, he has come to the dragon kingdom. However. No matter how hard, they could not defeat this kingdom, well, not even a few others in the past but the battle have caused so many destruction and darkness to loom all over the land.
Katsuki specifically told you to stay at a certain area at the palace, near your chambers, and in a relatively large safe zone so your be able to roam free, however. Katsuki as protective as ever, he knew that this battle is nothing you could handle. Sure you are capable of but he doesnt want to see a single scratch on you. With nothing else to do or protest you just simply obeyed... but then... a stealthy blood-thirsty assasin, Toga have managed to find you... but she left quickly before any knight could notice.
Katsuki have returned back at the palace when Shigaraki has left with his troops. The kingdom was damaged but it hasnt fallen down completely. Katsuki was greeted by the sight of servants nervously looking at him in concern, and pitty. He didnt know why but he shoved past them and entered your royal chambers immediately hoping to see you.
But then, the sight made shock and anger wash over to him. You, being unconscious in a pool of blood. Katsuki headed over to you to asses the situation, then fell onto his knees to get a closer contact. The wound may be deep although its a good thing you were still breathing. Katsuki held you close to his chest, breahing heavily in rage. "Those bastards..." he muttered under his breath with an unpleased tone. Kirishima was following just behind him, but as soon as he saw the situation he couldnt move any closer so he only stood by the door. He could tell that Katsuki is ready to kill someone by that look.