Conquest, so far, has several unique NPCs that you can recruit. The first one you'll encounter (on day 2, during the game's Prologue) is the halfkin bunny Daisy, whom you can purchase for a mere 100 gold. Her stats allow her to be turned into a pretty good whore, and the story/quest content helps you in this direction. But nothing forces you to use her as a whore. You can build her as a fighter or a mage or anything you want. The next unique NPC you encounter in the Prologue will be the elf Aire, though you won't be able to recruit her until much later on in Act 1 (and it's not easy to do). You'll encounter Princess Anastasia at the end of the Prologue, but she too cannot be recruited until you have completed several major quests in Act 1, and she plays a central role in the game's story. The orc mage Kurdan is the first unique NPC that you can recruit in Act 1. Orcs make great fighters but this one comes built as a mage (shaman). You of course can rebuild him if you wish to, which is what Oblivion potions are for. Kurdan, so far, has no story content other than when you first meet him. Last, but far from least, is the mage Zephyra (I forget offhand what race she is, fairy or something?) who also plays a key role in the story. There are several other named NPCs in the game, such as the guild leaders, but none of them are playable. Only the ones I've listed can join you.
Version 0.5.5 introduces the ability for the MC to marry someone. So far, you are only allowed one spouse, so choose carefully. And your slaves cannot marry each other. Not yet implemented, but currently in the works are special bonuses for the MC's spouse, and for the MC's chiildren.