Fullmetal Alchemist Volume 2 by Hiromu Arakawa
Brothers Edward and Alphonse Elric are in pursuit of something to heal them. Edward has a metal arm and a metal leg from when they tried to bring their mom back from the dead. Alphonse is now a soul trapped in a suit of armor, so he needs the fix even more. One of the other alchemists was developing the Philosopher's Stone, powerful enough to do amazing transmutations. As they search for the stone, they run into other alchemists of dubious character. The worst of all is a guy named Scar, who has been killing state alchemists because he thinks they are a blight on reality. Alchemy isn't natural, after all.
The quest for the Philosopher's Stone gives these stories a larger story arc, making the ongoing story more interesting for me. The rogue alchemist killing other alchemists also raises the stakes. I guess I'm hooked and will read more.