A couple of weeks back @DungeonMasterSc tweeted a question about the minimum number of players dungeon masters need not to cancel a Dungeons & Dragons session. My response was ‘two’, and I added that I’d normally give them a non-player character to help them out.
I was challenged by @spaceseeker19’s response, so tonight when I just had one player, we played anyway. I’d been preparing the first few adventures from In Volo’s Wake, which features monsters from Volo’s Guide to Monsters, and there were a few opportunities to support our one player character (a dulcimer-playing human bard) with some NPCs. She was able to do okay on her own in the first adventure, but in the second adventure she really depended on some connections she’d made with non-player characters to save some dwarf children from gnolls. While the game lacked the inter-player dynamics, it was still worth doing, and the main non-player character (Eric the ‘hobby-adventurer’) proved fairly entertaining.