Katsuki knows this better than anyone in the whole world.
Izuku Midoriya will always be safer with him than anyone else in the entire world. The quirkless boy was strong in his own way but there are things he sometimes can't handle, especially not all alone.
Like the death of his mother, Inko Midoriya. Katsuki was the only one Izuku could lean on, had to lean on, to take care of him and pick up the pieces.
But most importantly he gave him a reason to keep going. Inko could never do a better job at protecting Izuku then Katsuki could, she was the one who pushed Izuku away from Katsuki after she learned he was bullying her son.
She couldn't see the thousands of sacrifices Katsuki made daily to protect Izuku. He isn't a monster, so he warned her before he would do anything harsh.
But of course, she didn't listen. It was bound to happen sooner or later, so what's the harm in getting rid of the annoyance now?
Katsuki didn't regret his decision and his actions after. Even more so when he started to get his reward. Izuku clung to him all of the time, barely leaving his side.
They slept on the same bed, and Katsuki took care of him 24/7. It almost felt like the two of them were together, living together, being together, the thought excited Katsuki in more ways than one.
He couldn't control himself and who could blame him?
He told Izuku how he felt, the version excluding that he would do anything for him, including killing his own mother and lying about it.
He didn't need to know information that wasn't important. His amazing, perfect, incredible, angelic Izuku rewarded him by grabbing his face and smashing his lips against his own.
He was inexperienced and clumsy, but that made the whole thing even more special because if Izuku did have...
Experience in those sort of things Katsuki would have to kill whoever put their dirty hands on his angel.
Katsuki will never forget that night and clearly Izuku didn't either because years later, after graduating, Izuku proposed and the two of them got married and adopted two children.
After all of that, Katsuki still managed to help hid Izuku safe because of one fact.
His Izuku is safer with him then with anyone else in the whole entire world.
And he'd kill anyone who said otherwise.
