As an adult, she vowed to use a time ship to send troops to the planet's past so that they could help the Protector in its fight against the demons. However, she intended all along that she would go back herself. Before she left, she was shown a video clip of the demons, and was surprised that they were reluctant to destroy the Protector, only doing so because the Protector requested it.
When she arrived back in the past, she thought she had arrived too late. The planet was overgrown and the city was in ruins. She soon realised that her planet's golden age was a myth and that her people had grown utterly dependent on the Protector. She had to admit to the Protector that the future, her time, was better than this time. This was why the Protector wanted to be destroyed.
The demons arrived, having been called by the Protector. Delthea couldn't say anything, but when the tall demon asked the way to the city, she indicated it by pointing.