Sibling

"Fragment of a lingering will. Far down below us, beneath the kingdom, the air grows stiller and a sense of emptiness pervades. Can life flourish down there? If so, I will hunt it."

Siblings are enemies in Hollow Knight. They are the Shades inside Vessels which were let loose after their shells broke in the Abyss.

Behaviour and Tactics
Siblings will float towards the Knight when in range, dealing two Masks of contact damage. They occasionally spawn from the ground within the Abyss.

Upon obtaining Void Heart, they will become passive and no longer deal contact damage. If approached, they will curl and return back into the ground as if defeated. They will also die in 1 hit.

Hitting one with the Dream Nail will instantly defeat it.

Striking a Sibling does not grant SOUL.

Location
These enemies are very commonly found within the Abyss and Birthplace. The Siblings near the lighthouse will no longer appear after the lighthouse has been turned on.

Trivia

 * Cannot be read by the Dream Nail.
 * The Sibling is one of the few enemies that have various different looks, but no change to attacks, the others being the Fungified Husk, the Corpse Creeper, the Mistake, and the Royal Retainers.
 * Only a maximum of 5 siblings can be actively chasing the Knight at once; if a sixth one is trigged then one of the current 5 pursuing will break away from the group and go back to being idle.

References

Родственная душа Hermano Rodzeństwo