Hi, Leonard! Welcome to here!
First game is super exciting! This system takes a little adjustment, but once it clicks for a group, it really takes flight.
For this question, I’d look to the overindulgence in Vice rules for guidance. The Vice rules offer a variety of consequences for overindulgence. One is:
Lost. Your character vanishes for a few weeks. Play a different character until this one returns from their bender. When your character returns, they’ve also healed any harm they had.
It doesn’t seem like bending the rules too much to say “Cutter John is pretty seriously injured, so he’s going to sit this score out. Let’s treat this as if it were a deliberate overindulgence in Vice (Convalescence) and I’ll play Xephia the Leech this session. Maybe a couple sessions if it feels right for the story.” And then then have the Cutter eventually return with stress and harm cleared. (Note that this could easily be a lot more healing than the mere 2 ticks on the recovery clock per downtime you proposed! But then, bed rest seems at least as restorative as multi-week drinking binge.) This also feels in spirit with the GM’s idea of preparing a backup character.
A collaborative conversation with the group at the beginning of the next session when you’re rested and fresh seems like the way to resolve this. Figure out what will be the most fun precedent to establish and follow. What would feel contrived or artificial? What feels real and makes a good story?
It seems to me that an intent behind the Lost in Vice rule might be to encourage players to experiment with holding characters lightly and to engage with the story in a more authorial stance – to treat the campaign more as the story of the Crew than as the story of individual characters.
From this perspective, I think a house “Lost in Recovery” rule is in the spirit of the design.
But of course we don’t have guess! Blades in the Dark’s designer hosts this forum and we can just ask him.
Hey, @John_Harper!
What do you think of sidelining a character for a few sessions of recovery? Would you be comfortable sharing some of the design intent behind the “Lost in Vice” mechanic?