|"Is this all real? Or has this been happening inside my head?"
The topic of this article is of a real-life subject that has been mentioned "in-universe" in a canon source. The Harry Potter Wiki is written from the perspective that all information presented in canon is true (e.g., Hogwarts really exists), and, as such, details contained in this article may differ from real world facts.
The name "Henry" comes from the Germanic name Heimirich which meant "home ruler", composed of the elements heim "home" and ric "power, ruler". It was later commonly spelled Heinrich, with the spelling altered due to the influence of other Germanic names like Haganrich, in which the first element is hagan "enclosure".