AU where people form bonds with those they are close to, family, friends, mates (the closest bonds). The only way to break these bonds are if one person dies, or if something stresses the bond to the breaking point (you catch your partner cheating on you, etc). These bonds allow you to feel generally how the other person is, the closer the bond, the more you get. Losing a bond is extremely painful and you need to lean on your other bonds to recover.

Grindelwald captures Graves to steal his identity but anyone he has a bond with will know immediately. So he digs up a dark, forbidden spell that allows him to transfer Graves' bonds to himself leaving him with every one of his bonds broken.

Bonuses:
-Grindelwald really enjoys hurting Graves. In any way.
-After being rescued, he pulls away from everyone to avoid any new bonds that could be broken and just hurt more.
-Theseus/Graves or Newt/Graves post rescue, helping him heal from that trauma.
-Graves former bonded friends/family feeling violated by what Grindelwald did. Do those stolen bonds break as soon as he is revealed? Do they seek out Graves to try to form a new bond and does he allow it?