Mechanically, avoid overshadowing everyone else, and make sure you can contribute in combat. The rest will take care of itself.
Motivation-wise you need to be in Oakhurst and have a reason to explore the Sunless Citadel (some ideas below). Your character will also need to work with the rest of the party: loner-types make for great novels, but poor group games.
So, Why Explore?
Going for Glory: You are eager to make a name for yourself. The legend of the Sunless Citadel is well known locally, and stories indicate it is a perfect site for heroes intent on discovery, glory, and treasure!
Contracted: Another party of adventurers, locally based, delved into the Sunless Citadel a month past. They were never seen again. Two human members of that ill-fated adventuring party were brother and sister, Talgen Hucrele (a fighter) and Sharwyn Hucrele (a wizard). They were part of an important merchant family based in the town of Oakhurst. Kerowyn Hucrele, the matriarch of the family, offers salvage rights to you and your team if you can find and return with the two lost members of her family—or at least return the gold signet rings worn by the missing brother and sister.
Solving a Mystery: The goblin tribe infesting the nearby ruins (called the Sunless Citadel, though no one knows why) ransoms a single piece of magical fruit to the highest bidder in Oakhurst once every midsummer. They've been doing this for the last twelve years. The fruit, apparently an apple of perfect hue, heals those who suffer from any disease or other ailment. They sometimes plant the seeds at the center of each fruit, hoping to engender an enchanted apple tree. When the seeds germinate in their proper season, they produce a twiggy mass of twisted sapling stems. Not too long after the saplings reach 2 feet in height, they are stolen—every time. The townsfolk assume that the jealous goblins send out thieves to ensure their monopoly of enchanted fruit. You are interested in piercing the mystery associated with how wretched goblins could ever possess such a wonder, and how they steal every sprouting sapling grown from the enchanted fruit's seed. Moreover, you wish to find this rumored tree of healing, hoping to heal an ailing friend or relative.
I generally run alignment as a tag, not a moral persuasion. So you're “good” because Grampa fooled around with an angel, or “chaotic” because you fell in a vat of Limbo. If you want to play against alignment, go for it.
Sunless Citadel Home
Next time: Session 1