Squishy and Scales BKDK/DKBK EP2 Extra Illustration
Izuku and Katsuki have known each other for a LONG time. While Izuku himself is immune to jellyfish stings, he's developed special slime to counter the effects of jellyfish stings just to take care of his crazy best friend, who's always going out of his way to get him the best of jellyfishes for dinner~

For you, my heart. From you, my all. Chapter 4 P6-P8 Mermaid AU~! [Mermaid AU BKDK]

Katsuki does some crazy things for his squishy best friend~

For You My Heart, From You My All BkDk with alpha!Mer!Katsuki and Human!Deku~ 
Chapter 3 P25 Mermaid AU~!