Crowley's felt a sort of fondness for Alice since they'd met. She treated him much differently than the others did on the train, and after their little moment on the island, they had bonded. He couldn’t forget her so easily and even felt a need to protect her at times. He never had the urge to claim her as his, but to anyone else on the train, the relationship was obvious. He'd even gone so far as to make a space for her in his and Aziraphale’s room, just so she had a place to retreat to.

Crowley doesn't have a true concept of parents, but caring for Alice came naturally, all the same.

"It won't." she promises, giving her the same motherly squeeze she had in their illusion before letting go, a sentimental sort of look on her face. "You'll be strong for me, yes? We have to tell your father-- I mean, Ah--- Aziraphale next."

It still feels weird to talk like this. Crowley can still feel the full effect of the illusion in place beside her other memories sneaking in to confuse her.