On the one hand, Bellatrix and Lucius here with only the buffer of her seems potentially dangerous; on the other hand, if there is only the three of them, thank Merlin it's him. Besides, it's distracting, having to worry about him when she isn't sure where he is - it's much better just to know and be able to see that he's all right and focus on what's actually going wrong.

Which seems to be 'everything around them', come to that.

"Lucius!"