You're my # 1 || bkdk || bakudeku

Katsuki Bakugo, a teen basketball athlete; team captain .-He hates Izuku's guts, wants him gone-he pisses him off, and every time he sees him, he feels a wave of complicated emotions.- Izuku is just a nobody loser, someone who followed him around like a freak for years.- But now, Izuku is gaining friends, and confidence, he's growing.- Katsuki sees that, and he should be glad, shouldn't he? After all, maybe Izuku will finally leave him alone and run off to his new friends.-that's all he ever wanted, right?.- so why? Why does he hate the thought of Izuku no longer needing him.?

why is so afraid of being replaced as Izuku's #1

They both have complicated feelings about one another, and they both struggle to show them-especially Katsuki Bakugo. However, Katsuki's tough exterior is breaking, and Izuku is noticing that. Just a small slip of Katsuki's emotions spilling, and Izuku is quick to notice.
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Katsuki, despite everything, had a sharp tongue and a fierce temper.-it was better for Izuku to leave him alone, but, deep inside, Izuku couldn't ignore the spark of fear that flickered in Katsuki's red eyes as he stormed off.

Izuku realized Katsuki's exterior was close to breaking-The blonde athlete was about to spill his bottled-up feelings.

No quirks au! They're normal highschool students :)