Affectionate Nickname: If his friendship is high enough, Sten refers to the Warden as "kadan," meaning something akin to 'close to the heart.'.
The Ace: Evolves into this over the course of the game.
More literally, it's incredibly easy to accidentally start a romance with one of your eligible party members, as every romanceable party member has multiple dialogue options to start the romance, and many of them (such as "Are you feeling better about what happened to Marjolaine?" for Leliana) seem quite innocent on the surface.
A Human Noble is able to marry Queen Anora (if male) or soon-to-be-King Alistair (if female) during the Landsmeet.
You can accept yourself (as a male), convince Alistair/Loghain to do so, or refuse and sacrifice a Warden's life.
This is what Morrigan's Dark Ritual consists of.
A mage Warden who enters the Fade to confront the Desire Demon controlling Connor but then converses with her can be rewarded with sex, in exchange for the Demon being allowed to (or pretending to) leave.
Or, if you romanced and hardened Leliana, she will automatically invite herself along, and you can then invite Zevran. If female, you can invite a hardened Alistair to participate.
In particular, you can use it to persuade Isabela to teach you to be a Duelist without playing her game.
Accidental Pornomancer: On numerous occasions, you can actually use sex or marriage as a bargaining tool.
Their father abandoned his family to go to the surface, after Kalah refused to come with him to seek a better life from Orzammar.
Abusive Parents: Kalah, the mother of the Dwarf Commoner, is a verbally abusive drunk.
You can even achieve it with every single one of them at the same time, though most of them will be a strictly platonic adoration.
100% Adoration Rating: You can achieve this with any member of your party - it helps a lot when you're trying to romance one of them.
10-Minute Retirement: Between Origins and Awakening.