Sailormars is the soldier of fire, however, in the manga she was the soldier of war. Sailormars's attacks are of course fire-based. She is one of the strongest inner soldiers along with Sailorvenus in Sailorpluto's opinion anyway. At first Sailormars thought Sailormoon was a goof and shouldn't be leader of the sailor soldiers, while Sailormars thought she herself would be perfect for the job of leader. She has also had a crush on Mamoru (anime only), but forgot about it once Usagi was revealed to be Princess Serenity and Mamoru was Prince Endymion who were destined to be together.
Rei and Usagi constantly bicker, and one may think they hate each other, but they are really best friends. Rei just has trouble showing it. She is also suspected to be the inner soldier closest to Chibiusa. She, like Chibiusa, enjoys teasing Usagi about her grades, klutziness, and laziness, while Usagi likes to tease Rei about Yuuichirou, her grandfather's apprentice. Yuuichirou likes to sing and has a crush on Rei, but she can't stand his singing. Yuuichirou lets Rei get away with bossing him around all the time because he likes her so much. In the manga, Yuuichirou never existed, and Rei was a man hater, so it probably wouldn't have mattered if he existed or not.
Rei also has trouble with her own grandfather who is a perverted, old (well of course he's old ^_^) man. He constantly looks up the skirts of the girls that visit the shrine to buy good luck charms. He and Rei fought about this when an article was written about a perverted old man at the Hikawa Shrine.