Ok, obviously this is the start of a journey type fantasy (did I guess correctly?), perhaps in a country under a tyranical king? And you have two characters set up that are perhaps going to see a lot more of each?
It's a good start - but could certainly be better. More description would be great. Fantasy is a great genre because there's so much to describe - the world, the settings, the creatures. The people - we have Tristan's thoughts on Rose, but don't know what she looks like. We don't know eithur of their feelings, what inspires them to leave, what pushes them away.
Why are they together? What do they think of each other? These are some of the things that the reader will want to know - you may want to work them into the extract if you rewrite or (and would better) let the reader know it teh next part.
Great start.
-Anthas
