Thanatos makes a face when he tastes the drink, and he looks almost betrayed. (Ryo did warn him though.) Still, he drinks more from the mug before setting it down. If this could help him recover, it'd be worth it, but he can't tell if it's doing anything besides tasting horrible. Probably too soon to tell. He's not like Zagreus who can eat and feel better instantly.

Mort decidedly does not drink from the mug.