A reminder for writers writing Deaf characters:
Your Deaf character does not have to lose their hearing in a horrificly traumatic way, like a car accident, explosion, etc.
Most Deaf people have lost their hearing due to genetic factors, infections, ear infections, medications, medication overdoses, head injuries, and birth complications. A lot of this happened early on in life.
Having your Deaf character be fluent in ASL for the sake of being fluent yet having no exposure to the Deaf community and no one to sign with or who taught them doesn't make sense.
Keep in mind that a Deaf person who lost their hearing later vs lost their hearing young will have differerent life experiences; Deaf experience varies greatly.
Finally, just because your Deaf character is Deaf, it doesn't mean their life is miserable, pointless, unfullfilling, depressing, and only traumatic.
Deaf people have a rich history, culture, language. Many Deaf people don't consider themselves disabled and often consider it a language barrier (though this varies from person to person).
When you write a Deaf character, please do research and not just make their life what you think the Deaf experience is. Don't make a Deaf character's life just miserable because you like writing traumatized characters.
MINOR EDIT: ASL is also NOT a universal language. Sign language is different around the world and it defuses differently than English (since sign isn't visual English). For my post, I said ASL since I'm not knowledgeable about Deaf culture or sign language in other countries!