03 is a nameless soldier who was present at the murder of a member of the Barton family and then took his name, and his Gundam. Some believe that Trowa's real name is Triton Bloom, Cathrine Bloom's long lost brother. There is strong evidence for it, if you read Episode Zero. I don't really have a view, but there's an equal amount of people who believe that he's not related to her. I certainly thing the latter's more likely... Trowa is the silent stoic member, but he doesn't make friends lightly.

Trowa doesn't remember his past, but in Episode Zero there are a few flashbacks to a Circus, and a crashed Circus cart, suggesting that he was orphaned in that crash. Trowa has been a soldier as long as he can remember, and he'll fight and kill his friends if they become his enemy. He refuses to show emotion, to cry, for things, saying all his tears were used up when he was a baby. (Some might note that when he blows up Deathscythe he does cry, but that's later) As a child soldier (piloting a mobile suit) he meets Midii Une whom he befriends to some extent. However she helps betray him to get money to help her family. Trowa, for one of the first times in his life, shows a little emotion and pulls a gun on her (that's apparently how most people in GW show emotion...). She tells him that she wishes she was happy like him. Trowa is very confused, he isn't happy at all, is he? Midii explains that he has nothing to tie him down, and is happy. Trowa spares her, and decides to go to space.

I'm not sure how Trowa ended up working on Heavyarms, his Gundam, but he did. Trowa Bartonn (the real one) threatened to use Heavyarms for Operation Meteor, and was shot by a mechanic with family on Earth. Trowa offered to become Trowa, take his identity and pilot Heavyarms, because he'd grown fond of it, not because he wanted to use it for Operation Meteor. He took it to Earth, where he met Quatre in a fight. Quatre, realising that they shouldn't be fighting, surrendered to Trowa, and then Trowa surrendered to Quatre, and there was basic surrendering all around. No, really, they just became friends, and Quatre had Trowa over to his house for tea. Trowa has a tendency to infultrate the enemy organisations although the first time, with OZ, it is unclear whether he was infultrating them, or whether he actually joined. Before his loyalty could be really (blowing up Duo's Gundam doesn't count) tested, Quatre blew him up. Trowa survived, but lost his memory. He was found by Catherine Bloom and went to work in the circus as a clown (see the background pic) and the guy who gets knives thrown at him. Catherine tried to get him to stop fighting, but was unsuccessful. He didn't regain his memory for quite a while after re-joining with the other pilots.

Trowa's Gundam, Heavyarms, works basically on the principal of guns, and lots of them. Heavyarms' arms are both large guns, and he has a pair in it's chest. He also carries a beam saber thing (Oooo, Star Wars). He is very acrobatic, and can usually be seen doing his signature flip, which he can also perform in Heavyarms (someone has too much time on their hands...) He uses a gun (like everyone), so he must carry that around with him. And, of course, there's his skill at knife dodging. He rather unnerves Catherine when she's throwing at him. She realises he wants her to miss, and to kill him, causing her to miss and knick his cheek (see background pic). I'm sure he could dodge knives if he felt so inclined.