Here is a list of all canon things in my book. None of it it canon in the actual show
(unless proven otherwise)

ABOUT DEAN
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The only time he ever calls Jenny by her real name (Jennifer) is usually when he is scared.
Dean tries his best to not say werewolf around Jenny, since he knows it's one of the only monsters she's afraid to talk about/come in contact with.
Dean was actually the one to get Jenny to stay with him and John and continue to go on hunts together, not John.
Sam has caught Jenny and Dean dancing to Footloose and Grease on more than one occasion. (It will possibly be brought up in book 2, which is already published.)
Dean actually enjoys listening to the Tetris theme song, since it always reminds him of Jenny.
Dean's biggest fear is either being alone,
or having to choose between Jenny and Sam.
Dean is constantly worried about Jenny since she always seems to have good intentions, but always fucks up her plan and gets hurt in the process.

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ABOUT SAM
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it has not been mentioned since the third/fourth chapter, but at one point, Sam had called Jenny buggy because of her love fore insects. He probably grew out of calling her that.
Sam did at one point have a small crush on Jenny, possibly when they were kids, but since that one chapter where he was 'possessed,' he hasn't mentioned or shown that he likes Jenny.
Sam would never be able to choose between Jenny and Dean, even if their lives were being threatened. He would rather them both die than have to watch as one realizes they aren't as loved by him.
Sam would definitely kill a regular person for Jenny. But he wouldn't do it for Dean.
Sam prefers hugs from Jenny.

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ABOUT JENNY
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Her favorite song is Wheel In The Sky by Journey
She's scared of big dogs like pitbulls, mastiffs and great danes, but she loves German Shepherds and Rottweiler's
She can't stay mad at anyone forever, unless you killed someone she cares about.
Her biggest fear is losing Dean, so she'd rather sacrifice herself if it meant saving him, even if Dean called her a hypocrite for not letting him do the same.
No matter how many times she wears them, Jenny will never learn how to properly walk in heels. And yet, she still buys them.
As seen in many chapters, Jenny adores children and is always ready to step in to save them. Even if it cost her her life, she would risk it for a child she has. ever even seen. (i'm conclusion, she'd be a great fucking mil— Mom. she'd be a great mom.)
She's always wanted to hold a squirrel, so she settles for Dean because he doesn't run away from her.
Her first kiss was a girl.
She has never called Bobby 'Dad,' despite seeing him as her father.
Bobby occasionally calls her Jenny-Bug for the same reasons Sam used to call her Buggy.
At one point, she tried to run to Canada, but was arrested for crossing the border with a fake passport. John bailed her out of jail.
After dropping out of high school, instead of Hunting, she worked at a Baskin Robins for a year and was employee of the month.
She was fired from Baskin Robins after throwing hot fudge at a rude customer.
Jenny has an emergency fund account in the likely case everyone she knows dies and she goes on to live a normal life.
Jenny used to be very excited every-time she found a case. And then she started going on cases with John.
Jenny is an idiot when it comes to her own safety.
The Dagger that she frequently uses helps her tune into her sixth sense, making it easier for her to handle the sick feeling she gets when she senses a monster. But, in order to use the dagger in a way to see ghosts, she has to tap into her negative emotions. When she is around the dagger, she tends to be a ticking time bomb of anger or sadness.

I'll be honest i was waiting for someone to point out that Dean only ever calls her Jennifer when he's scared but none of you have yet 🧍🏻‍♀️