Disclaimer: Square owns the characters, but you knew that already.
Tifa's strength has always been what fascinated Red XIII. Her slender frame conceals her power well and it pleases him to see her unleash it in such a precise manner. A quick jab or kick and a grown man will fall to his knees, weeping like a child whose toy has just been taken away. The only fault he can see is her inability to hurt the one who hurts her the most. Day after day, without fail, her eyes will brighten at the sight of him and she'll ask how he is. Cloud will stare at her with dead eyes before walking away and Tifa can never hide the pain that flickers across her face.
During the brief yet poignant moments like these, Red XIII wishes he had the strength to help her.