Alena's idea of a 'soldier' is completely different from Snake's. When Alena heard Snake describe himself as a 'soldier', she immediately thought: "OH, he's some loyal knight of a kingdom and he's worried about what must be happening there without him." That is, Alena thought Snake was a little weird when they first met because he seemed distant and had weird thought processes/priorities, but then when he said "I'm a soldier," she reacted with: "Oh, that explains why he's weird." The reasons behind this are:
1. Alena's royalty and most of the soldiers she's known have been guards or incredibly devoted knights who have been stationed in the distant outskirts of the Kingdom where not a lot of people go, let alone live.
2. One of Alena's chief traveling companions (named Ragnar) is another incredibly devoted knight who started a solo journey far away from his homeland (to search for the fabled hero/ine) for no real reason other than he thought it was his duty. Alena values her personal freedom, and so probably couldn't see herself doing that, but respects the dedication.
So, Alena associated Snake's description of himself with that. Maybe it's not too far off in the long run?

But Alena likes talking with him and thinks he's a good Knight to know. It's good to have an experienced fighter to spar with. :|b

Reverse?