agon-

(Greek: struggle, a contest, to contend for a prize; also, to lead, set in motion, drive, conduct, guide, govern; to do, to act; by extension, pain)

tritagonist (s) (noun), tritagonists (pl)
In ancient Greek drama, the third actor, whose part is usually that of the evil genius or as a promoter of the sufferings of the protagonist: In his lively readings of ancient Greek dramas, Dr. Cooper used a shrill voice when he represented the tritagonist talking.
unantagonistic (adjective), more unantagonistic, most unantagonistic
Not opposed, not antagonistic: Ivy thought that her grandmother was unantagonistic, calm, peaceful, and never angry.
unantagonized (adjective) (not comparable)
Regarding the opposite of pestering or opposing someone; not antagonized: Jim was completely unantagonized and untouched by the remarks made by the other children.

Cross references of word families related directly, or indirectly, to: "master, lead, leading, ruler, ruling, govern": -agogic; arch-; -crat; dom-; gov-; magist-; poten-; regi-; tyran-.