She was slow to make friends--not shy, but diffident and suspicious.

Her friendship once secured was a thing worth possessing.

She was inclined to bestow it upon this quiet, self-contained English girl.

In such matters the length of an acquaintance goes for nothing.

A long acquaintanceship does not necessarily mean friendship--one being the result of circumstance, the other of selection.
"The princess knows Russian ?" said Catrina suddenly.
She was standing near the dressing-table, where she had been absently attending to the candles.