It's just a matter of what you're looking for. I'm attractive and fun and good in bed. In our kind of situation, with all the stress of being kidnapped and experimented on, it's nice to get out some of that anxiety with something fun and healthy like sex. But not everyone's looking for relationships or complications. I never lie about who I am and what I want, but I'm just as capable of hanging out as friends. I like people and I like sex and I'm relaxed with whatever. They like the lack of pressure and the encouragement of having a good time without needing to worry about consequences.
That's what I think at least, you could always ask one of them.