Okay, in order:
All she has to do is look:
Euphoric at the rush of absorbing the hunter's life, Ahri felt more alive than ever, and traveled Ionia in search of more victims. She relished toying with her prey, shifting their emotions before consuming their life essence. She alternated between dazzling them with visions of beauty, hallucinations of deep longing, and occasionally dreams colored by raw sorrow.
...
Ahri shut her eyes and reached out to the reservoirs of magic around her. The environment had plenty ripe for the taking, but she was too weakened by the tea to draw them to her. Instead, she reached into Hirin's mind, which was far more malleable, and pushed.
Ahri opened her eyes and stared hard into Hirin's. They deepened from lavender to violet.
"Hirin," she said. "Come closer. I would look into the face of the one who tricked me."
"Of course, lady," Hirin replied, transfixed. The woman's voice sounded hollow, as though it came from the bottom of a well.
She leaned in until her face was only inches away. Ahri inhaled, drawing essences of the woman's life from her breath.
...Hirin was a young girl hiding, hungry and afraid, beneath a market stall. Two men argued above, looking for her. She had nothing but empty coffers to show for her days' work...
Ahri continued to drain Hirin's life, sampling memories of raw emotion. They felt rich in Ahri's mouth, and she relished each unique flavor of emotion.
Essence Theft in lore:
Ahri tested her self-control by consuming small quantities of life essence, enough to absorb a memory or two but not enough to kill. She was successful, for a time, but was tortured by her unending hunger and soon succumbed to temptation, indulging in the dreams of an entire coastal village.