Starlight had moved in. She hadn't seen the door. She'd never met it, never made mention of it.
Twilight wondered if she should have told her. It made sense. Starlight would stay in the castle, so she'd have time to check on it. Starlight was smart. Downright brilliant. It would be a great opportunity to study it, and maybe finally understand it.
All she had to do was speak. Right in that moment, if she wanted to. The door was there after all. Behind Starlight, as the unicorn sat to eat dinner with her. No reason not to tell her.
Twilight opened her mouth to speak, but the heat from the spoonful of soup she brought to her lips made her flinch. Enough for the door to disappear. She could always wait for the next time.