A Tarnished Halo
"For fools rush in where angels have fallen through the floorboards once already . . ."
Characterization and Interaction
I arrived late to the cause of supernatural characters, but it's now fair to say that I have been in the club for long enough to make up for the lost time. Although I still haven't read it, I am intrigued by (my take on) a number of the plot devices of Terry Pratchett and Neil Gaiman's Good Omens – namely that a posting to Earth is enough to motivate agents of both Paradise (which is boring in comparison) and Perdition (which is more boring than you'd think) not only to covet staying on earth, but even to work (in small and subtle ways) against the interests of their superiors, if doing so contributes to the aforementioned end. Of course, no motivation will apply equally to everyone. Use your imagination: those running the show on both sides are bound to overlook some "spotty behavior" when it comes from well-placed operatives with otherwise-good track records. I'm running with that idea.
Of course, if you didn't already know "Pieter" was really a Celestial, you wouldn't know just by looking at him. The play never needs to involve supernatural elements. Honestly, I enjoy writing about the things that Pieter's characterization would naturally suggest. Take a cue from the casual exchange you "overheard" in one of the vignettes – don't pull any punches, and don't be afraid that Pieter sometimes remembers to wear his "wedding" ring.
It follows that supernaturals on opposite sides of the supposed "alignment gap" can (but don't always) get along fine while doing their thing on the "front lines" among the Normals. After all, Earth is the place to be! Why make a scene and draw undue attention? (This premise extends to other supernaturals who might be engaging in the same masquerade as Celestials and Infernals: aliens, deific avatars, djinni-kind, fae-folk, ghosts, lycans, plane-walkers, psionicists, shape-shifters, time-travelers, valkyries, vampires, witches and wizards, etc.) By itself, this doesn't make any of them disloyal – they still do their jobs when called to do so. It just makes them more self-interested than you'd think.
The Fine Print
Many people strive for "original" and "creative" without making sure they have "entertaining" covered. Come correct when setting your role-play priorities.
Don't hide behind a screen name. If you know who I am, then tell me who you are.
I can't compete with your misconceptions. If you somehow "know all about me" even though we've never met, then we both need to question why.
My mother did not give birth to a fool or to a doormat. With that said, exceeding my patience is difficult. Breaking my trust is only slightly less difficult. (I sincerely believe both of those things.) Redeeming yourself fully once you have managed to exceed my patience or break my trust is more difficult than both of those things combined.
Unlike some self-proclaimed "elitests" I've seen, I'm elite enough to spell the word "elitist" correctly. That's about all anyone should need.
Don't roleplay like you used to. Roleplay like you want to, and everything else will take care of itself.