"I feel like I was waiting all by myself to meet you..." Mamoru says to Usagi during the R Movie. I have to wonder what young Mamoru was like. A mystery to us all. The only stuff we are shown of him is from the Sailormoon R Movie. I get the impression that when he was young he was more apt to display his emotions, for example his outward tears at the parting of Fiore. I would assume he began to keep his emotions more inwardly as he grew older, without parents, at the orphanage. He could have been made fun of for being emotional or something and simply learned to hide them within himself. This would explain Mamoru's bad communication skills in the series. We know that grown-up Mamoru clearly still experiences these emotions, but tends to hide them from others, sometimes causing misunderstanding. But even this sad, confused, thoughtful child may not be close to what he was like before the accident. Was he happy, outgoing, loving?
It's impossible to know since Takeuchi-san never wrote about it and Mamoru himself can't remember a thing before the accident. One wonders though, if his memories of his previous life returned, why can he still not remember anything before his parents from his present life died? Is it because symbolically none of it is that important because Usagi was not in it?
The Symbolic Quality of the Rose
Tuxedo Kamen's signature weapon and symbol is the steel-tipped rose. His main duty is to protect Sailormoon and the senshi. Because of his general lack of power in the anime, he will throw himself into attacks, taking the blast for his fellow senshi so that they will still be able to perform and defeat. The senshi's attacks all come from some planetary or mythological origin, so what does Tuxedo Kamen's rose stand for? My theory originates in the Sailormoon R Movie.
Though they will still be strangers to one another for a decade to come, Usagi and Mamoru unknowingly first meet in the hospital. Two happenings bring them together - one joyful, and one tragic. That in and of itself is symbolic - Usagi's joyous event to accompany her joyous personality, and a tragedy to accompany Mamoru's silent, inward personality. Shingo's birth brings Usagi there with a bouquet of red roses intended for her mother. On the other hand, Mamoru has just survived an accident that took his parents and memory away from him. Passing by his room and seeing the young boy cry, Usagi approaches and rests her head on his knee. "Don't cry..." she says. She then tells him about her newborn brother, then offers him a rose from her bouquet. Afterwards, Mamoru gives the same rose to Fiore as a goodbye gift.
The rose symbolizes Usagi's kindness and understanding. I think (though this is just my own theory) that Tuxedo Kamen's roses can be seen an acknowledgement or tribute to the pure love and kindness that Usagi presented him with on their true first meeting, even if neither one of them really remember the encounter.