When Aragorn first appears to us he is nothing but a cloaked man of mystery. He sits in the corner of the Prancing Pony covered in shadow as he stares creepily out at the world… particularly at the group of hobbits.
When Frodo asks his name, the innkeeper says that folks around here call him Strider. Yikes. Basically, he appears to be exactly the kind of person your parents warned you to stay away from (especially if they offer you candy). So when he grabs Frodo and forces him into a room upstairs, we're imagining the worst.
But hey, he turns out to be all right. In fact, he's better than all right—he saves their lives.
We learn a lot about Aragorn pretty quickly. He knows about Gandalf and he tells the hobbits the story of the Nazgûl. He's pretty much a walking Middle-earth Wikipedia—his wisdom probably springs from all the wandering around he does.
All that wandering around also makes him an outdoorsman (they don't call him a ranger for nothing): we see him bringing a dead deer back to camp. He's also a swordsman—he's able to single-handedly fend off five Nazgûl on Weathertop.
But all beneath all that manly man swagger, he's forlorn when he sings the Lay of Luthien. He's a complicated man.
The fact that Aragorn has noble blood running through his veins comes out bit by bit—foreshadowed by a dramatic close up on Aragorn's face when Elrond explains that the heir of Gondor has chosen a life of exile. We finally learn from Legolas that Strider is no mere Ranger who just happens to be smooching the elven king's 3,000-year-old daughter. He's the descendant of Elendil and Isildur, and heir to the throne of Gondor.
But we don't really see much of Aragorn in his kingly form during Fellowship. He tells Legolas to stop jibber-jabbering about the throne of Gondor; he clearly wants to distance himself from his identity as royalty. But it's clear he has some stature amongst the elves in Rivendell and Lothlórien, and we end the movie with the distinct feeling that it won't be too long before Aragorn will have to show his true royal colors.