Andromeda had turned a corner not that far from the library (not that she knew it at that moment) when she ran into someone that she recognised. Bellatrix, which apart of her was happy about but mostly she just was confused at the influx of emotions she felt at the sight of her older sister. She also noticed the smile as quickly as it disappeared which didn't help matters.
"Bella," she said automatically smiling herself before frowning slightly.