On the topic of pronouns, deadntwoames, etc.
It's really not difficult to call someone thier name. As a cis person with an unusual name, I've had people try to "rename me" to make it easier for them and I've insisted that my name is my name. Same deal.
If you slip up, then correct yourself, apologize and move on. Trans people know it happens, and while they might be annoyed, they're not likely to string you up if it was a one time innocent mistake.
It's your sincerity that matters most.
And yes, it's harder if you knew the person pre-transition. And it's also harder if they're earlier in their transition and their presentation resonates in your brain as different from their preferred pronouns. It's harder for them too.
And it may be hard when telling a story and they went by a different name/pronouns in that time. It may be confusing.
But it's really not a big ask to call someone by the name/pronouns that they want.
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