Daemon Gender
From Daemon Wiki
It is thought by some people that daemons don't have a specific sex, seeing as most are visualized without any visible genitalia, and if they were corporeal it is thought that they would not need to use said non-existent genitalia for sexual intercourse, as they are thought to not do that (see daemons and sex).
However, it is thought that daemons generally are the opposite gender from their human. However, they can be the same gender or androgynous. It is thought that people with daemons of the same gender are necessarily homosexual or bisexual, but this is not true. Straight people have been known to have daemons of the same gender.
It is thought that the gender of a daemon reflects what the person needs. For example, if a male human who is mostly in male company, and is masculine, would possibly have a female daemon to contrast to him and give him the feminine input that he may possibly need. Another example could be a female human who is mostly in male company, and is somewhat of a tomboy. She could possibly have a daemon of the same gender to her, perhaps to reflect her possibly masculine nature.
That said, there is no proof as to why daemons take a specific gender for a person's specific needs, the reasons for that are usually determined by the daemians themselves individually.