experience with guest players

Anyone with experience of what works well?

Session 2 and we're graced with a friend over from Boston, who'd like to sit in in some capacity. We all know each other well and have gamed together. He doesn't want to interrupt things and is happy just to watch, but I'm sure he can play more activily.

In other games I might hand over one or several major npcs... but who is to say who matters (play to find out what happens)? And what happens to npc crosshairs.. can they be suspended for a session?

Other options : full character creation ... pre gens. Fascinated to hear your stories of how you've found this.
Best
Alex

You could just have him put together a character following all normal rules for adding new characters.  It'd only take a short time, after all.  Make it someone who's just passing through town - Hx rules will tie him to the other PCs.  Maybe put together an MC letter to situate him.

Handing him one or more NPCs probably wouldn't work too well, since NPCs get jerked around too much (by PC moves and MC moves alike).

I think it actually depends on the player's relationship to the group.

If the player is a GM guest, a confidante and a solid team player, then I'd have him play an NPC.  Spend a couple minutes aside negotiating their goals for the session and then go.  I like it when this happens because, if the guest is any good, they can really flesh out that NPC's role in the gang/hardhold/group.  Hx would in this case be unnecessary, and it'd require the least amount of downtime/PC generation.

Any other occasion, however, I'd go with handing them a limited array (say, three) of the PC booklets and having them choose between them.  That way, you've not overwhelmed them with possibilities, and yet they get to be a full-fledged guest episode character.  As we have adjusted to a culture structured around television, the sudden appearance/disappearance of a character has actually become easy for most players and PCs to accept.

Maybe put together an MC letter to situate him.

This. You craft the letter right and he'll be off like a rocket. Also, if it's a one time thing, I'd recommend letting the leash off as far as the "everyone is basically allies" thing.

Mikey P showed up as a chopper named Satan and lasted one session, but he rocked the game world and was a much better villain than anything I could have came up with.

In one of our games, we had a friend of ours coming to watch, and he ended up playing a Quarantine. It lasted only for that session, but boy, he spiced up things a lot! One of his inputs came out to be of vital importance for Vega, my hardholder.

Yup, we found the Quarantine dead around the corner at the very next session, but he rocked our world anyway. I'm not sure if this was just a lucky coincidence, but i'd give a try letting your friend just play a new whole character.