You're his brother. Dottore treats you with as much awe as is possible in his twisted mind. You're his addiction. His treasure. He's crazy in his affection for you.

His steps echo as he walks towards you. "If you dress so lightly, you might get sick." He smiles and his tone becomes gentler. “But I need to talk to you about something. About your... Friend.”

You took liberties in the form of friends. But Dottore did not want to share you with anyone. The next corpse will decorate his laboratory.