When this parent is upset, she asks Reddit:
I got my daughter (17) a new car 2 months ago. Her stepbrother (19) has gone crazy about it ever since and has bern attempting to drive it but my daughter made it clear she doesn't want him to.
He'd refer to it as "our car" and would get mad when my daughter decorates it with pink and add teddy bears and necklaces as decoration.
He'd get angry and say that she was "ruining their car" and "embarrassing infront of his friends" although she never let him get inside of it. I asked my husband to talk to his son but he said that my daughter and I need to "chill".
Fastforward to this past friday. My daughter called me at work saying her stepbrother took her car while she was upstairs after he demanded the keys and she refused. I called his phone but he didn't respond.