She was also Lobsang's legal guardian.
Selena was described by Joshua as "certainly attractive".
In December 2030, she's the one who set up Joshua's first meeting with Lobsang (speaking to him through a soda vending machine).
After a brief discussion about Joshua's past, Step Day, the origin of Lobsang and what they wanted from him, she led Joshua to meet Lobsang in person. She wasn't able to go with Joshua all the way because she only has a security clearance of five despite the fact that she's been working for the transEarth Institute since the start.
In June 2040, with the trolls gone, when Lobsang summoned Joshua Valienté, who hasn't spoken with Lobsang for years, for a face to face meeting, Selena waged with Hiroe, another transEarth employee, that Joshua would not come.