Irena is a character introduced in Part 12 of Servant of the Siphen and also in the second part of The Maw of Despair.
In my original notes she is named Princess Arianne, which is a not so clever play on the name Orion, which is what she names herself when she meets the crew of the Orion for real.
Just as we humans sometimes create avatars to interact with each other online, Irena is an avatar of the Orion’s computer, designed to interact with humans. In the distant past, when her original crew was still alive, she would have taken the form of their race to interact with them.
Irena is (as far as she knows) the last of her kind. The Orion and starships like her were designed to act as the sentinels of the dimensional portals, the only ones trusted to open them to travellers and traders. Avatars act as a second stage of authentication to prevent anyone from simply hacking the computer to learn how to open the portals.
When Caroline and Rhona go on a virtual reality adventure to pass the time, Irena hacks into the VR system, sets up a suitable scenario and plays the role of the princess needing to be rescued. It’s not just a test though – after many years of isolation, drifting between the stars waiting to be rescued and repaired, Irena is bored and lonely too.
Avatars are grown and cybernetically augmented on board the ship. The augmentation creates a secure link between the ship’s computer and the avatar, and interferes with any kind of thought or brainwave scanning.
However, avatars are otherwise as limited in capabilities as the genetic template they are based on – they are mortal and can die from illness, injury or old age. Perhaps whoever created the technology recognised that in order to earn the trust allotted to them, they should not be given any more advantages.