Just a dialogue between two characters; calling the one who does most of the talking a "narrator" is a stretch, as a narrator is supposed to address the audience rather than other characters.
So I perhaps haven't described it in completeness, and the portal example is misleading because video games don't have quite a traditional narrator.
In particular, the narrator is narrating in the traditional sense: directly describing the actions and emotions of the main character in the second person, while also describing their own actions/emotions in the first person. That's the bit that is confusing me - it's a first person narration or a 2nd person narrative, or some such...
You took the phone call, though you knew the risks as well as anyone. "It'll be all right" you said as the click of the phone receiver stretched into silence, but I knew that you were lying.