He's not a teen refugee, but he's not exactly a grungy mercenary is he? How would he find himself in this caravan- a group of carts filled with children and teens, protected by some worn out mercenaries and city guards no longer fit for hard combat? 
[i][color=ed1c24]Self interest, suits him better then travelling alone.
He would have lied, bribed or threatened anyone he had to.
I didn't want to make him any younger because of his level of skill in magic. But if your happy with it I can.[/color][/i]

Personality section is a bit sparse, but serviceable. If Vallen was bought from his father by a performing troupe, how did he also take his father's "greatest masterpiece" with him? Its also almost [i]too [/i]convenient that his father's greatest work was a set of throwing knives- which Vallen happened to learned how to use while in the troupe. A Royal smith crafting weapons for nobles and knights? Giving them daggers as opposed to fine swords?- I feel like it would make more sense for his masterpiece to be a single piece. 
[i][color=ed1c24]It also makes sense that they would be the last item to sell, as you said they all want swords and such. It wasn't his 'greatest' master piece just 'another' master piece and it was bought by the troupe before kidnapping Vallen. When he found out it was his fathers he wanted them.
If you feel it fits the story better he could have trained with them knowing they were his fathers.[/color][/i]




Just a side note on ages, if we are comparing to medievil times, 18 wasn't exactly a helpless teenager either.
Adult hood, work and marriage, all came about between 12 and 16. Pretty much everyone here is an able bodied fighter. (Princess exluded.)