Two fire signs together are pure intensity: passion, initiative, zero boredom. You understand each other's urgency to live. The obvious risk: two flames compete for the same oxygen — learning to yield center stage is what makes this last.
Two fixed signs: loyalty that survives anything… and two stubborn heads. In agreement, nothing moves you — together you're immovable. In disagreement, nobody yields. Learning to let go first, even sometimes, is your lesson.