Glimmer is not domineering in bed. Actually, she wants her partner to strongly take the lead and control the situation, but she does not know this consciously. How does this square against her aggressive personality as a villian? Well, due to abandonment issues (the Sunburst issue, or maybe her father) she feels a latent sense of strong insecurity. To compensate, at the subconscious level, she seeks to control everyone and everything around her. This substitutes, artificially, for an internal sense of security. However, when she meets somepony with greater emotional power and resolve than her, but who seeks her welfare, this can substitute for a sense of internal security. This security thus established, she becomes more passive. It can happen this way with a lover or maybe with a friend (like the friendship between Twilight and Glimmer that resulted in Glimmer calming down substantially). Thoughts?