It's a Wizard NPC who's lying on a bed in his secret hideaway, wearing a ring of sustenance, using Scouting Summons and Extend Spell metamagic to be out and about with no risk to his actual body.
My first though was Draconic Ally so he's living as a medium dragon for weeks at a time with no risk to his actual body, but it might not work since it doesn't have the word "summon" in the name. The other options would be something with a 10min/lv duration (doubled by Extend Spell), which isn't nearly as useful since were dealing with 4 hours per casting at L12.
It's still be an interesting character concept I thought I'd share that would work for a variety of NPC types:
1: a cowardly scholar who only leaves his study this way because he's afraid of the outside world
2: An adrenaline junkie who likes to be on the edge, and this way he can push it past the point of fatality to really know how far he can go, and still be fine.
3: A crafty recurring villain who knows the risks of the deals he's making, and this gives him a level of anonymity and protection against anyone who might double-cross him.