Claiming is the act of taking telepathic control of a Sundered One.
It requires training and willpower on the part of the human, and is one of the key purposes of the Academy.
Claiming is only possible because Powerful but broken creatures, enslaved to keep mankind alive in a flooded world. SUNDERED ONES ACCORDING TO HARRY The Sundered Ones appeared at the same time as the deadly black... More are what the humans call “broken;” something is very wrong with these creatures, and a human with steady, strong concentration can impose their will onto a Sundered.
If successful, a claim results in the Sundered One’s neural processes being connected to the human. The human can command the Sundered One to do anything; the only two limitations are the power of the particular Sundered (depending on tier) and the willpower and creativity of the human.