Woge

Woge (VOH-gə; Germ. Wogen "surge"), named from the psychological impulse that drives it, refers to the act of morphing into one's Wesen form; it is used as a gerund. In the Grimm series, English-speaking Wesen disregard the grammatical rules surrounding verbs, using anglicized forms "woge" and "woges". As Woge is impulse-driven, a dead Wesen will woge back (or "retract") into human form. Likewise, a Wesen tends to enter Woge once they perceive something as a threat come close to their vicinity. As such, to voluntarily enter one without necessary cause could take a while, as seen in, where it took Monroe a few seconds to shift into his Blutbad form.

Most Wesen can voluntarily woge by rolling their heads or other specific movements. A Grimm will also see this.

Varying degrees of woge
Woge can occur in different degrees, a higher degree of woge yielding a more complete transformation. Many Wesen have been observed partially transforming, and most known Wesen have been observed transforming only to a degree detectable by a Grimm. One particular Wesen, the Jägerbar, has even been observed in a complete transformation into a grizzly bear. Apparently, Wesen can tell if their own is being truthful or not via their woge, as seen in. Monroe and Holly demonstrated being able to shift partially by localizing the Woge around their eyes, turning them into a fiery red color. Others have only partially woged before, such as Doug Shellow morphing only his arm in.

Wieder Wesen
Wieder Wesen are Wesen who have mastered control of their Woge. Wieder Wesen often adopt an entirely lifestyle, either by choice or out of necessity. For example, the Wieder Blutbad Monroe switched to a vegan diet to help himself avoid having to confront his Woge, while the Wieder Spinnetod Charlotte experiences the effects of rapid aging since she is unable to molt without consuming human entrails. She also refrains from wearing shiny things, because Spinnetoden are attracted to them and she is resisting her impulses.

Loss of Woge ability
In Hexenbiester, the ingestion of a Grimm's blood causes the Wesen within the individual to die, and the person is unable to woge into a Wesen form again, effectively rendering the person a normal human.

Woge retraction disorder
In some rare cases, a Wesen may not be able to retract or woge back following the transformation. Four such cases were caused by a sudden drop in supply from a subcutaneous drug pump that pumped homeopathic herbs, spices, and traces steroid amounts into the bloodstream of Wildermänner. This was also accompanied by a wild rampage.