hi! i was wondering what the differenc between fictionkin and fictive is? also, what is a headmate?

Headmate: Any conscious and separate entity sharing the body of another conscious and separate entity. The root word here is ‘roommate’. Basically using a room as a metaphor for the mind. Two or more people share the same ‘head’ together. All fictives are headmates, but not all headmates are fictives. Non-fictive headmates are often called ‘in-sourced’.  A group of headmates sharing one body are referred to as a ‘system’ or ‘multiple system’. 

Fictive: A headmate in a multiple system who has a fictional origin. For example Cloud Strife. A Cloud Strife fictive would share headspace with other fictives or insourced system members. He would have a concrete identity as Cloud, with all or most of his memories from his ‘canon’ in tact. 

Fictionkin: A person, either a singlet, or a headmate in a multiple system who identifies as a fictional character either spiritually or psychologically. For example, believing that you were that character in a past life.

Read here for a more in depth analysis of the difference between fictives and fictionkin.