I saw this going two ways so I'll do both

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*Middle of the Liberation war* 

Kay: *gets knocked down, coughing slightly and hurt* 

Shigaraki: *grins, reaching down to decay her*

Kay: *trying to get up, but was close to passing out* 

Bakugou: *comes from behind Kay, using his explosion* She's MINE!! 

Shigaraki: *backs up, the explosion in his face* 

Bakugou: *grabs Kay and keeps her away from Shigaraki* You stay away from her, it's not her time! 

Kay: *in and out of it* K..Katsuki...

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*After Liberation war* 

Koy: Come on, let's take you back.

Best Jeanist: Koy, you can't...

Koy: What? 

Best Jeanist: *grabs Mei's shoulder* She can't be taken back...not after all she's done... *looks at Mei* I'm sorry...come on... 

Mei: *looks down sadly* I...I understan-

Koy: No. You're not taking her...she's mine, she's coming back to the dorms...

Endeavor: Koy, don't make this-

Koy: *uses his quirk, making the ground shake like an earthquake* 

Best Jeanist: *losses his balance, letting go of Mei* 

Mei: Whoa! *falls back* 

Koy: *catches her, holding her close* She's MINE!! *tears up* 

Mei: *looks up at him* Koy... 

Hawks: *flies above the ground* Kid, calm down-

Koy: You stay away, it's not her time!! *doesn't let Mei go*