Luffy got caught by the marine and akainu got the order to break his will. Akainu puts him in the same cell ace was in

Akainu: How does it feel? Being in the same cell of your death brother?

akainu has obviously fun on playing with luffy this mind game to break him

Luffy: don't you dare mention him! Your the one who killed him! He sacrificed himself for me!

Akainu: Now that we talk about him! I could just kill you right now! The same way I killed him~

akainu makes a Magma fist. Luffy gasped afraid, his trauma slowly but surely coming back to him as he sees the Magma first