Light
There were many things about Lucy that made Erza think of light. Her hair for one since it was blonde. Erza loved the way Lucy's hair would shine when they were laying out in the sun. They would laugh and enjoy their time together, but Erza was so focused on her hair. She always thought Lucy was an angel. She just radiated. Another thing was the magic she used. When Lucy uses her keys, you can see a bright light. Erza never saw Lucy using any kind of dark magic. Lucy made every day better for Erza. Even if she woke up in a bad mood, Lucy was there with a bright shining smile for her. It made everything so much better. Lighter even. Just thinking about Lucy made Erza smile. Erza was laying beside Lucy right now and the sun was starting to shine through the window. It illuminated everything in the room. Lucy looked as if she had a slight glow on her face.
'Even more like an angel.' Erza thought as she put a caressing hand on Lucy's cheek. She felt so much warmth right now. 'You really are the light that guides me Lucy.'