She cuts her hair

Seizing the opportunity to gather additional intelligence, Hermione, with a deft wave of her wand, conjured a razor-sharp blade. She proceeded to cut off all of Bellatrix Lestrange's hair, ensuring to preserve some for later use in a Polyjuice Potion. The dark tresses fell to the ground, symbolizing a symbolic act of control and dominance.

Once Bellatrix was left with shorn hair, Hermione expertly secured the captured locks and stashed them away, a potent ingredient for the disguise she would later adopt. With a combination of magical restraints and strategic spellwork, Hermione escorted the now disheveled Bellatrix to a hidden dungeon within the lair, ensuring that her captive would remain confined and unable to alert others to the intrusion.

As Hermione carefully concealed Bellatrix in the depths of the dungeon, she left the captured Death Eater with a silent promise – a vow that her actions would serve a greater purpose in the fight against Voldemort's tyranny. The stage was set for Hermione to assume Bellatrix's identity, using the Polyjuice Potion to infiltrate the Death Eaters and gather information that could tip the scales in favor of the resistance.