You mentioned that fallen!Aziraphale likes to play pranks on people, what kinds of 'pranks' are we talking here?; whatever they may be, they won't stop me from showing this soft, owl-man some love (Apologies for all these questions about your Zira, he's just too interesting).
His pranks are mostly harmless, but can be quite annoying. There’s the typical gluing coins to the ground, changing or removing the signs of push or pull doors, and there’s classic shock toy pranks. Small stuff. Oh, but he does enjoy doing more elaborate ones. Like adding googly eyes to all of Crowley’s plants or taping things to the ceiling! Tasteless, but mostly harmless.
Also, no need to apologise! It’s a lot of fun to come up with all this even though I hadn’t planned to go into further detail other than the designs :P Thank you for asking!