Frustrating love (bakudeku)

Katsuki has deemed Izuku a rival for 12 years. He doesn't understand why Izuku seems so far ahead of him.
But what if someone told him what he was feeling sounded like a crush...

Izuku has always admired Katsuki. That was never a secret. Although recently, he's been feeling strange around him. He's glad their relationship is getting better, but it won't go anywhere if he feels like his heart will explode when he goes near him.

What will happen as the two figure out they have feelings for one another.

Are they going to come to terms with? Or will they deny everything.

Will they tell the other?

And what'll happen when a new student joins their class?

This is the same universe as another book called The Frustration Of Loving.
You can read this without reading the other because it's basically the same story just in bkdk's perspective... this might be smutty depending on whether I can write smut or not. I have written smut b4. I'm just rlly bad at it.
But if you were wondering what they were doing all those time Todoroki saw them (or didn't), then here you go!