How we cite our quotes: (Line)
Quote #7
MARTIN: Oh. So—you knew each other even before high school then, huh?
EDDIE: No, see, I never even knew I had a sister until it was too late.
MARTIN: How do you mean?
EDDIE: Well, by the time I found out we'd already—you know—fooled around. (471-474)
Now we're getting the backstory on how these two half-siblings ended up in a sexytimes (read: incestuous) relationship with each other. It seems that they had already developed an affection for each other before the Old Man's bigamy-loving ways were discovered.
Quote #8
MARTIN: And you fooled around in high school together?
EDDIE: Yeah. Sure. Everybody fooled around in high school. Didn't you?
MARTIN: No. I never did.
EDDIE: Maybe you should have, Martin.
MARTIN: Well, not with my sister.
EDDIE: No, I wouldn't recommend that. (486-491)
Even though he's hardly the poster child for a healthy sex life, Eddie is basically looking down on Martin for not "fooling around" in high school. Martin, for his part, doesn't really mind having missed out on the fooling around, since it meant he avoided sleeping with his sister.
Quote #9
MARTIN: Well, how come you didn't know each other until high school then?
EDDIE: He had two separate lives. That's how come. Two completely separate lives. He'd live with me and my mother for a while and then he'd disappear and go live with her and her mother for a while.
THE OLD MAN: Now don't be too hard on me, boy. It can happen to the best of us. (495-497)
Now Eddie is getting into the dirty (ish) details about how Eddie and May managed to meet and get interested in each other before realizing they were siblings—that is, how their father was able to deceive everyone long enough for that to happen.