Seclude multiple characters?

I’m trying to make an AI on a website that contains multiple characters. Done so in the past easily but for this AI all the characters interact with the user individually, one at a time. However when I try interacting with the AI it responds as different characters from the one I’m supposed to be interacting with. Any advice for phrases or code to add to the AIs description to seclude the different characters and remember the one the user is interacting with at the given moment?