I think emilia would have woken subaru in that case. Her mental age is 14, which includes the six years she spent in elior forest with puck and the single year she was at roswaal's mansion before. Echidna hates emilia because she is the child of the person she loves with another woman, thats why even her existence is so painful to her why is echidna on such.
Emilia was frozen when she was 7, not 15. Comunidad donde se comparte contenido multimedia de la hermosa emilia vizcarra. A compilation of evidence that emilia's mother is minerva.
But there's the usual issues with emilia mother theories, such as emilia being 115 while minerva died 400. And because subaru doesn't seem to confront. This is just a list i made of every piece of information or fact supporting this theory, and it is not supposed to be. Emilia is currently his goal, due to his initial dying wish, to save emilia.
Emilia is taking far longer than it should to answer subaru's confession because she thinks it's ok. Rem acts as his greater emotional support, allowing what is anordinary person to continue in the face of the rbd despair. Additionally, emilia claimed in the wn that the name minerva made her nostalgic. That's where emilia and subaru come in.