Keltham appears within the mirror, glances at the apparent camera location, and casts from scroll a Greater Scry of his own. His eyes within the mirror focus then on the two devils, and don't particularly seem to see Abrogail - not in the fashion of ignoring her, but in the fashion of Abrogail not being visible to his scry at all.
"Is the living mortal Abrogail Thrune II, who was born to that name and compacted with the god Asmodeus and once signed a compact with myself, present nearby and ready imminently to be interrogated by you, in accordance with that agreement made between myself and Hell one hour and thirteen minutes earlier in the mortal realm?"
...there's only stars visible behind him, in the mirror, in the scry radius around him; and there's something wrong with those stars, they are too many and too bright.