The Angelic Race was created to serve the gods loyally and without failure. They were created after the First Servant, thus made with perfect bodies and brilliant and strong wings.
With time, the Race became expert in near all areas, doing whatever their masters, mostly even creators, wished them to do. Legend tells, though, that they desired freedom to truly be a perfect race. Some wished it so dearly taht they turned against their masters, and through that, the Angelic War begun, spanning two entire worlds. Several Angels lost their sanity, and some gods were utterly defeated during the war.
Angels that maddened are for example Sorrath, who destroyed his master, a sun-god, and took control for himself, or Landra Andros that became such a threat to the gods that they banished her in to a mountain of ice. Countless others fell from grace and a few still roam the worlds, having survived the war somehow.
After the war, the Angelic Race was free. They left their old homelands and created their own. Near all still serve the Gods, but they chose on their own who they serve, and they do it willingly, not because they were merely created to do so. With a free will, though, some angels wander the worlds on their own due to curiosity or thirst of knowlege.
The Angels have created a language that is highly complex, but through it's complexity it is meant to prevent any sort of misunderstanding. This evolved from the original task of the messengers bringing orders from their god to the reciepient.
Spoken, it seems like the language is a song. Written, it is like a complex painting, extremely hard to decipher or even tell that it is a language if one is unfamiliar with it.