One last note on Portal & Lilith's Brood

After I posted my piece on the incredible similarities between Portal and Lilith's Brood, another thing hit me:

Neither Chell nor Lilith can exit their prison cell. They must wait for their captors to open doors or walls for them. Eventually, their captors give them this ability, but it's still limited compared to what the captors can do. Even with more "freedom," they're still both trapped.