It was neutral, impassive and even, after a while, strangely companionate and reassuring, although I did notice that its calm exterior sometimes slipped and that it occasionally mirrored my own unexpressed emotion.
Era neutral, impasible e incluso,  después de un rato, extrañamente sociable  y tranquilizadora, aunque me di cuenta de que  su exterior tranquilo a veces resbalaba y que ocasionalmente reflejaba  mi propia emoción inexpresada.