"The Looming Stranger"
While a growing number of trainers appear to have one of these mysterious beings in their employ, none can recollect precisely how or why the relationship began, as specific, detailed memories pertaining to the beings simply fail to form. Those regularly associating with a Longfellow can readily recall the outcomes of its actions - such as whether or not it successfully neutralized a threat - but never the actions themselves. Even those who survive an aggressive close encounter with the Longfellow cannot remember how it inflicted its signature spiral-shaped scars, but may suffer a long-term sense of being followed or watched, and many who have crossed one seem to disappear without a trace.
A Longfellow is only faintly visible from any angle but the front, and all witnesses - even recording devices - simultaneously perceive its "cap" angled towards the viewer, hiding whatever "head" or "face" it may possess and sometimes illuminated from behind by an intense, white light of unknown nature. Scanning equipment reads the monster as a freezing cold, empty space.