OK, before I start explaining, this is my own personal opinion! So if you have a problem with it, please write me a lovely flame that will be added to this site. Now, onto the explaining!... There are a lot of similarities and differences between these two. Both of them are pretty laid back characters, but I don't think Duo is as laid back at Usagi ^_^::: They both joke around, and can be serious when they need to be. Say these two were to meet. Now, let's put Mamoru aside here, let's say hes out of the picture!   Usagi would probably find Duo cute and attractive, (who wouldn't?). She might have a clutz attack or do something embarassing, but Duo would probably just laugh about it and give her a hand if she were to have one. I'm sure these two would start off as great friends. Duo, I don't think would be that mean to Usagi  when she has her cry baby moments and her fighting with Rei or ChibiUsa. He would probably just  give a sigh and say something to her in a nice way, possibly a cute little sweat drop ^^. He would have patience with her and respect her. I think they would start off as great friends then get into a relationship
	Now, Usagi would love to joke around with Duo like buddy-buddy. In the future, these two would probably develope a crush on eachother and not admit it until something dramatic happens to them. Usagi would be totally commited to Duo and I believe Duo would be the same exact way. Usagi wouldn't like it when Duo would have to go up to space and fight or become violent by killing people. I can see her being very sensitive about that issue. She would probably talk to him about it to find another way to make peace, but Duo would just explain to her about the war and so on. Oh! another thing too! Duo is known as 'Shinigami' and Usagi is known as, well a varitey of things. But with some imagination. Duo could help Sailor Moon by being Shinigami! o.0...yeah weird, I know but its the creativity.