What's Persona about? It sounds interesting.
It depends on the game in question, but the general sum-up of the Persona series is this: Several people, usually high-school students, gain the ability to harness Personas, the embodiment of what is essentially their psyches, in order to face some conflict (often demons or beings called shadows). In the original games (1, 2, and 2: Eternal Punishment) the personas are called out, and in the later ones, they are summoned via some medium (a device called an Evoker in 3 and as cards in 4).
The persona changes as the user does, and as the user starts to peel away the mask that they put on for society, they start to reveal their true selves which, ironically, allows their personas to grow as well. Generally the personas are based off of beings in urban legends, religious beliefs, stories, and mythical creatures. Some of them you guys may know, such as
Izanagi,
Orpheus,
Lucifer,
Shiisaa,
Gabriel, so on and so forth.
The games are pretty amazing and I definitely recommend that those of you who haven't played any of them do so. Heck, I'm sure if you like Pokemon you'll like the Persona games. Not to mention that the games (as well as the entire Megami Tensei franchise) has great characters, music, stories, and themes. Heck, I'd even say that Persona 4 is probably one of my favorite games of all time. As for which one to start with, don't worry about it. While all of the games are in the same universe, none of the games (barring the 2-part game "Persona 2") require the player to have played the previous games in the series to understand them, though it is worth noting that Persona 3 and 4 made some radical (and highly praised) changes to the gameplay that aren't present in 1 and 2.
Alternatively, if you don't want to play the games, you could check out Persona 4 The Animation. I don't think it's a substitute, really, but it's a good show that prompts emotional response.
...I dunno if I presented the series well enough, and if there's someone who can explain it better, please do. I will say this, though: Persona is an incredibly appropriate series to be turned into an RP, and I definitely think what Doronjo has cooking is worth check out.