I doubt he ever went to Ishbal, either. Al makes a point that because there was so much of Marcoh's research (a whole pile of documents), he couldn't simply run off with them, and that's partly the reason he hid them in the 1st branch library in Central.
So would Scar want to kill him after all? Even if Scar's given up on killing State Alchemists, Marcoh isn't technically on his list of targets. But then again, Marcoh is responsible for making the incomplete Philosopher's Stones that killed a lot of Ishbalans, and he'll admit to it too....
Also, Marcoh says that many State Alchemists gave up their licenses after the rebellion because they couldn't bear being used as human weapons. I wonder if Scar went after them too...?
Marcoh says that Ed may be able to create a complete Philosopher's Stone...does this have to do with why he is a human sacrifice? Candidates are those who may be able to open the Doors...what if it's the same with creating a complete Philosopher's Stone? Note that I'm saying 'complete', because there were lot's of incomplete Philosopher's Stones being created in the past. I'm thinking that the reason they're incomplete is because to make a complete one, you'd need a whole lot more sacrifices than some prisoners on death row. Like...an entire civilization of sacrifices on the scale of Xerxes.
Which is why Father can't just go creating a new Philosopher's Stone for Lust. Not anytime soon, anyway. If he is indeed planning on using the people of Amestris to make a new Stone, then it might be possible. But otherwise, any other Philosopher's Stone would be faulty and incomplete; something worth giving to the likes of Cornello, but not in creating a homunculus.
And lastly, Marcoh says of Ed and Al's goal..."I cannot let you have the Stone for something as minor as that." So basically he's saying that it's not worth the sacrifice of so many lives for such a small purpose. Later on, Ed and Al think so too when they learn of Hughes's death, even considering giving up their quest if it means other people will be in danger. And in Chapter 56, Ed is still inwardly unsure about using the Philosopher's Stone to get back Al's body because it uses the Xerxes peoples' souls....and back in Chapter 8 again, Ed says he didn't want to take the Stone that helps the people in Marcoh's village, because even if they get their bodies back that way, it'll "leave a bad taste." Is that how they'll feel if they do end up using the Philosopher's Stone to get through the Doors?
(Incidentally, they faced the same moral dilemma in episode 22 of the anime; Ed was hesitant at first about using the Stone, but Tucker convinced him with basically the same argument that Envy did in Chapter 53. And then the issue really isn't brought up again even when Al himself becomes the Stone, and they freely go about using it to restore each other's bodies.)
...You know, the homunculi sure do like taking hostages. D: For Marcoh, they're taking a village hostage, Riza for Roy, Winry for Ed and Al. So Envy's taunting of Marcoh could go for Roy and the Elric brothers too; they're putting thousands of people at risk for just one individual....it's understandable in human terms, because Roy doesn't want to lose anymore subordinates, and Winry is like family; to Ed and Al, family is everything. But still, I can kinda understand why the homunculi would think humans are 'foolish'...
And uh...an inconsistency. >>;
Me: hey, do you remember why Lust wanted to destroy Marcoh's research documents in the anime?
Kirsten: Why? :O
Me: because now that I think about it, that was just stupid. she wanted Ed to make the Philosopher's Stone, right? in the manga, she burned the library down because she didn't want him to learn anything 'unnecessary.'
Kirsten: .........WTF BONES
Me: sometimes I wish the anime took more liberties when it comes to things like that, just so it'll make more sense. >.>;
Me: and then later on in episode 22 they're all like "Hahaha we knew you would come here >D" even though just a while ago they were sabotaging their own plans