I ran a game that had a Seelie/Unseelie court in it. I took obvious traits of Summer/Spring (Seelie) and Winter/Fall (Unseelie) and personified them into two courts.
Things Seelie: Life, Food (Gluttony!), Heat (Fire!), Beauty (Vanity), Rebirth, and Work (Planting Season) among others.
Things Unseelie: Cold, Death (Repose too), Rest, Frugality, Hunger, and Patience among others.
I liked to take each aspect of the seasons and figure out what the aspect is when taken to a good extreme (such as Frugality of Unseelie) and have a Fae that represents it (All about conservation and planning) and a Fae that represents the evil extreme of the same attribute (all about greed and hoarding).
All of them I aligned NE or NG. N tends to denote a close tie to nature, following nature's laws, while still being free of civilizations laws-thus neutral. This also tied them very closely to the druids who had to have a neutral alignment, this is a plus!
I always played them as very aloof and misunderstanding (or not caring) of human limitations, not really worrying about mind controlling or even hurting humans if it serves there in-born fae purpose: this makes all mortals very wary of dealing with them.
As a complete side not, the Courts (ruling councils) themselves in my game were based on the pieces of a Chess set: in fact the game in my campaign world was a game based on the "struggle of unseelie versus seelie". There were always a queen and king, each with an advisor (bishop), champion (knight), and Devoted Problemsolver aka assassin/spymaster/chief bodyguard (Rook). Each court also had eight lesser lords that oversaw the affairs of the courts subjects (the pawns). The court of the Seelie ruled 6 months out of the year, and the Court of the Unseelie ruled the rest.
Hope I've given someone some good ideas.