"I am." She told him, crossing her arms defiantly. "Our parents thought me killed as an infant, but I was raised in secret in the exiled Tenth Realm of Heven, amongst the warrior angels. So, yes. I am your sister."
She looked him over, glad that he seemed to be more level-headed than the version of him she knew from THIS world.
"I realize that you and I, being of differing realities, are only blood via a technicality, but I would still like to help you adjust here."