You could put the Blair and Harriet fact in their bio, in the FAMILY section if you want. The rest of them are fine as fun little facts.
Both of these should go in their character bios, respectively. Like you should mention in his backstory that he was interested in studying medicine and biology. Also, in his Mothers bio in the FAMILY section, you should mention that his mother was nice to him, but it was just the ideals of the time.
I think the second fact should go into Tommy's section only because it does sound like he hates him when that really isn't the case. Other than that, I think everything is fine, maybe you could mention the gender dysphoria somewhere earlier in his bio, only so that people don't question whether or not he knows about it.
That makes sense, but now that you've said this you have to come up with something about his mother. What is she doing since she doesn't want the police involved? Is she doing her own sleuthing and figuring out where the daughter is (that could lead to an emotional plot event)? Is she worrying her butt off and spiraling into a downward swirl of depression, blaming herself for the loss of her daughter, who you said she loves very much, and Harriett is the one who is witnessing this? You can use this and go down a lot of different routes with this. You don't have to do this, but it's just an idea.
I like how you explained why he is the way he is. If you edit this, make it less wordy, and find a way to make the traits transition into each other or into a paragraph(s), I really think you'll be able to put this in the PERSONALITY section, or even downright replace it depending on how you write it. I think this because this reveals soo much about him and it is very helpful in understanding Braxton and helps the reader relate to him more.
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Wow, Elkisgreat you really know what you're doing, and it is very evident that you thought this character out along with the world he lives in, and all I can do is applaud you! Thank you so much for letting me review him! And thank you guys, the readers, so so much for reading my book! Subscribe to my profile for more updates on chapter and other books, vote this chapter if you really liked it and if you want, go ahead and drop your on OC in the "Form" chapter, which is the very first one. I will do what I can to review your OC and give you as much honest advice as possible. That's that Space Cats <3