"Tragedy and trauma makes your character more interesting."

In the long line of things people have misunderstood is the idea that terrible things in a character's past inherently makes them more interesting or adds depth. Tragedy is great, it's a wonderful tool, but it's not a chainsaw you can use to cut your story down to perfection, but rather a scalpel you have to use very carefully.

Your character being an orphan doesn't fix a sloppy backstory. Your character's dad being an alcoholic doesn't change the fact that you wrote a Gary Stu or Mary Sue. Parent death isn't the only way to add some problems to a character's past.

Sexual trauma doesn't fix bad writing and it isn't something you should just throw into a character concept unless you have the ability and willingness to really explore the horror of something like sexual assault.

Mental disorders don't fix a boring or stupid character concept, especially if your writing makes it clear you don't possess any particular knowledge, understanding, or experience with said mental disorder. Mostly, I find it pretty offensive how mental disorders in RPs and writing tend to just be very surface level and stereotypical descriptions that serve to further some pretty poor understandings of neuroatypicality. Related, psychopaths and sociopaths as characters are getting pretty droll, it takes some serious thinking and writing to pull these types of characters off well without just looking like you're writing a walking example of pop-culture stereotypes.

All that being said, having horrible things happen to your characters is a great thing for writing, just make sure you have the ability, knowledge, and energy to really dig deep into the implications of the trauma you inflict on your characters.