The same-
I think there are more doors in this hall. I think there's no need to fixate on that one.
Other options:
no subject
The same-
[His head jerks up quick, surprised. He'd forgotten anyone else, for a second, was here. It's a second more, maybe two, before he replies.]
I think there are more doors in this hall. I think there's no need to fixate on that one.