The corner of Leif's mouth curved up into a smirk, though not unkindly. Satu, at least, projected coherent thoughts. Not merely 'cheesecake' at ridiculous volumes. "I would if I could," was the most sincere answer she was likely to get, and even then it wasn't exactly dripping with honesty. He would if he could, but only for as long as it suited him. Otherwise, there was little point in being a telepath. 'You know it won't end well if you laugh at her.' And that was why he hadn't. Leif had forgotten what Dagmar had been like when she was Satu's age. Kajsa's adolescence was no longer a part of his memory, since she didn't actually amount to anything and never would. Unfortunately, the sarcasm of demonic water elementals at his little sister's age tapped right into Leif's more consumer friendly sense of humour.
"... Hello." Honestly, he was of the opinion that acknowledging the other person's existence was greeting enough, but apparently this instance required more. Well, it wasn't exactly a chore. It was just a touch jarring when he was greeted like he wasn't the pariah of the family. He was vaguely aware of the effect the height difference may have had. So he made a point of not merely staring down at her. Satu was his sister, not a pleb from the street or an employee under his thumb. She was also requesting - demanding, really - to be taught blood magic. Linnea would be so damn proud. "It's definitely blood magic you want to learn." More like a statement that required confirmation than a question. "I only ask because your mastery requires a human sacrifice. Otherwise, I don't see why I couldn't teach you." He was quite deliberately treating it as a business transaction, and mostly because he refused to treat her like a child. The last time he had pretended to be child-friendly, he had cursed the brat.