Unfortunately, your adult sister may still thrive on being the proverbial thorn in Avoid making assumptions regarding why your sister is being irritating, even.
My youngest worshiped his older brother, who had nothing but disdain and often undisguised hatred for his little brother. The youngest is an Aspie, so he never.
Sometimes even as adults, sisters can be irritating. has likely noticed the behavior your sister displays that annoys you and it may even annoy them as well.