The TVTropes Trope Finder is where you can come to ask questions like "Do we have this one?" and "What's the trope about...?" Trying to rediscover a long lost show or other medium but need a little help? Head to Media Finder and try your luck there. Want to propose a new trope? You should be over at You Know, That Thing Where.
Having an inaccurate dream based on secondhand info is something that normally happens in Real Life, so we can't say what the narrative significance (what makes it a trope at all) is without further info. Does the exact way B appears in C's dream tell us something about C's psyche? (Maybe a metaphorical description of B is taken literally, showing that C is Literal-Minded, or a wacky off-the-walls interpretation shows C is a Cloud Cuckoolander.)
If it doesn't reveal anything about C, it could just be because Real Dreams are Weirder, or maybe it's a case of Anxiety Dreams. Or if the story initially looks like C's imaginary B is inexplicably like the real deal, before veering off into nonsense, that would be a subversion of Psychic Dreams for Everyone.
The meeting between A and B is only shown to the reader through a flashback by A describing the meeting to C. During C's Anxiety Dreams B explicitly states that C only knows what A told him about B. B is very warm and friendly in the flashback, but A is Incorruptible Pure Pureness, so that could be his biases colouring the flashback. She's significantly less friendly (and looks slightly different) in the dream due to the stress C is under (and him being more cynical with light shades of Know-Nothing Know-It-All).
I can put something in Anxiety Dreams on the main page, so thank you for that suggestion. I'm just looking for something to put on B's page to show that even the reader can't be certain about anything regarding her personality or her appearance, because it's all secondhand info.
Edited by commoduscrassius
That could be a variation on The Ghost, I think.
Seems perfect. Thanks
Character A meets Character B in real life. They describe the encounter to Character C. Character C later dreams about Character B. Character B has a significantly different personalty and appearance in the dream compared to real life, owing to the fact it is only based on Character A's description. Is there a trope that can describe this for Character B's character page?