Scar's brother was messing around with alchemy. He was trying to bring someone back, like Ed and Al. He disappeared during the Ishibal(sp?) massacre so it seems, so where did he go? Then along comes Lust, who Scar says looks like the person his brother was trying to bring back. It has been discussed here that Ed and Al's father may have created the Sins. So, is it just coinidence that Lust looks like Scar's brother's girlfriend/wife/whatever or could it be that Ed and Al's father is Scar's brother?
Just total randomness, but tell me what you think!