Grimmchild

Grimmchild is a Charm in Hollow Knight. It summons the Grimmchild which deals damage depending on its phase.

Usefulness
When equipped, the Grimmchild will float around behind the Knight. In its first phase, it does nothing else. However, collecting Flames will allow 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 will activate 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 will initiate a boss fight with him. Upon defeating Grimm, the Grimmchild is upgraded and can deal 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 requires no combat to collect. 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 can deal 11 damage.

Trivia

 * Grimmchild will try to attack Millibelle when she is at her bank in Fog Canyon, as well as the Hunter during his first encounter in Greenpath. This deals no damage to either of them, but will prevent being able to use Millibelle's banking service.
 * When resting at a bench, the Grimmchild companion will rest on the ground beside the Knight.
 * If the Knight is too far from the Grimmchild, there will be a short animation of it teleporting back to the Knight.
 * It is suggested that after Nightmare King Grimm has been defeated, the Grimmchild will eventually grow up to replace Grimm.

References

Niño_de_Grimm Мрачное дитя Dziecię Grimma L'héritier de Grimm