Grimmchild

Grimmchild is a Charm in Hollow Knight. It summons the Grimmchild which deals varying levels of damage depending on its Phase.

Usefulness
When equipped, the Grimmchild floats behind the Knight. In its first Phase, it does nothing else. However, collecting Flames allows for upgrading it to Phases 2, 3, and 4. In these Phases, the Grimmchild shoots a fireball at enemies that deal increasing damage at each Phase.

Wearing Grimmchild activates unique dialogue when speaking with the White Lady.

How to Acquire
Grimmchild is given by Troupe Master Grimm in Dirtmouth after the Grimm Troupe has been summoned. Having Grimmchild equipped reveals three flames around Hallownest. These can be absorbed by the Grimmchild after defeating the Grimmkin Novices which guard them. Returning to Grimm after this upgrades the Grimmchild, causing it to deal 5 damage.

After this, three more flames can be collected which are guarded by Grimmkin Masters. Subsequently returning to Grimm initiates a boss fight with him. Upon defeating Grimm, the Grimmchild is upgraded and deals 8 damage.

Finally, three more flames which are guarded by Grimmkin Nightmares have to be collected. There is also a fourth flame in Deepnest which can be collected by talking to Brumm, requiring no combat. Having three flames and then using the Dream Nail on Grimm starts the fight with Nightmare King Grimm. When he is defeated, the Grimmchild is in its final form and deals 11 damage.

Trivia

 * If Grimmchild is not in its first Phase, it tries to attack the Hunter during his first encounter in Greenpath and Millibelle when she is at her bank in Fog Canyon. This deals no damage to either of them, but does prevent the Knight from using Millibelle's banking service.
 * Regardless of Grimmchild's Phase, this also causes Weaverlings and Hatchlings to attack her, though they do not prevent the Knight from using her services.
 * When resting at a Bench, the Grimmchild companion rests on the ground beside the Knight.
 * If the Knight is too far from the Grimmchild, there is a short animation of it teleporting back to the Knight.
 * If Grimmchild is equipped in Godhome, the Grimmchild does not appear to aid the Knight in fights against Troupe Master Grimm and Nightmare King Grimm.
 * Grimmchild not appearing during battles against Troupe Master Grimm and Nightmare King Grimm has no effect on whether the Knight is Overcharmed.
 * It is suggested that after Nightmare King Grimm has been defeated, the Grimmchild will eventually grow up to replace Grimm.