What gave Alice strength was a new realization.

—I will fight for what I, myself, seek for from now on. I will fight to
protect my little sister and my parents, along with the people of
the Human World who Kirito and Eugeo hoped to protect.

Alice vividly felt the remaining doubts about herself and her sense
of futility disappear into a white light deep in her heart. That light
surged through her, finally accumulating at her right eye, covered
by that black patch, and generating an intense heat.

“………!”

She clenched her teeth as she withstood a fierce pain that shot to
her eye socket from the back of her head. But that pain somehow
nostalgic, or heartrending. Alice gripped the bandage across her
head with her left hand and took it off all at once.

Her right eyelid that had been closed since that day nearly half a
year ago opened slowly. A red light expanded from the center of
her dark vision and eventually turned into flicking flames. Visions
of houses lit aflame overlapped and gradually closed in on each
other—finally finishing as one.

(Alicization Invading, 101)