High-pitched ringing or a blur of images (subway trains, office lights, a hospital bed).

Seeing an object that looks exactly like something from Earth (a toy, a book, or a specific tool).

Memories don't usually just pop up for no reason. Pick a catalyst: A minor head injury or a fever dream.

Don't just list facts. Describe the physical sensation of two lives colliding:

Catching their reflection and realizing their face doesn't match the "soul" they feel inside. 2. The Mental Sensory Overload

They have to act like a normal child so people don't think they're possessed.

Feeling the grief of a previous death while simultaneously feeling the small, young body they are currently in. 3. The "Wait, Where Am I?" Moment