Headcanon: (TW also because I have PTSD and he’s one of my comfort characters)
Bakugou and you are really close, one day you’re studying and he gets annoyed because you weren’t understanding something and so he starts yelling. He goes to grab your hand to show you how to do it, but you flinch away, covering your ears with a fearful look. He looks at you confused and reaches for you again, but you flinch away once more. He’s always noticed how you flinch or tense up when it gets to loud, or flinch away slightly when someone touches you. He never thought to much about it, assuming it was just because you weren’t expecting it. But now he knows it’s not the case. So he growls, and in a quieter voice this time. (Though he’s very obviously angry) he looks at you and asks “Who?” You look at him confused so he repeats the question “Who hurt you.” So you tell him that your ex/parent/step parent abused you. He then decides to hold you tightly, you guys watch movies the rest of the night. From then on he tries to speak quieter around you, not yelling and trying to keep others from getting to loud. He’s also become even more protective of you, growling and glaring if someone gets to close to you, or tries to touch you.