Hail brother,
I personally do not recommend the pendulum method. Why? From self experience, a gray or other enemy entity can cause you to be fed false information and results are naturally not as inclusive as the following method:
A great way to discover who you Guardian Demon is,(discovered by HP Mageson/Don Danko) is first look for the gender you are most attracted to. This is a comfortability thing to ensure the maximum closeness between your guardian and you. Even the most bi of bisexuals have a preference. Now that you know the gender, look on the demons page on the JOS website. Read their descriptions and see which one/ones match your personality the most. You should look in both the "High Ranking" and "Other Gods" pages, because hey, you never know. Look for the one that jumps out at you the most. Once you've narrowed this down to say one or two you should begin to ask yourself: "Am I fully comfortable with ________ as my GD?" If you answer "No" then he/she is probably not your Guardian Demon. If you answer "Yes" but still feel like you need to keep looking for a GD, then, again, you probably haven't found yours.
A Guardian Demon is one of the best gifts Father can give his dedicated children. But you do NOT pick yours. Once you do the dedication ritual and have done some work to show that you are not souly doing this for personal gain, a Demon will personally choose to guide and guard you. More often than not our Guardian Demons try to make contact with us but we are just not open enough. An easy way to know for sure if you think you know whom yours is, is to enter a trance state and call out(vibrate) the Demons name(like 40 times). Then sit comfortably and ask him/her if they are your guardian demon and will guide and guard you from now on. If they are and have accepted to be, you will feel a warm glow engulf you and the feeling of comfort will arise. This is such a blissful feeling.
Hail Father! Hail Agares and Raum! Hail to our Legions!
