Sid knew the Handmaiden… the Blood Sister… quite well.
Her name was Felise. The two of them had been at the Academy together, and arrived at the Dark City at the same time.
There were many others that year, as well… although not everyone made it to the Bright Castle alive. Those who had either turned out to be lucky enough to become Guards or were left to rot in the outer settlement.
Sid and Felise were not lucky, but they happened to possess a few soul shards by then, so they paid the tribute and entered the Castle together. Naturally, they stuck close to each other once inside.
Their shards did not last long, though. Eventually, they had nothing left to pay tribute with… that day, Sid decided to leave for the outer settlement, while Felise decided to become a Handmaiden.
Sid did not blame her for that decision. Felise was… a soft girl. The harsh life in the outer settlement would be a death sentence for someone like her, most likely.