Aslan Timeline and Summary

Aslan appears next to Jill as Eustace falls from the cliff; he sends Eustace to Narnia on his breath.
He waits for Jill by the stream and insists that she drink.
After Jill confesses her part in Eustace's fall, Aslan tells her about the lost prince and gives her the four signs, making her memorize them before sending her to Narnia.
Aslan appears to Jill in a dream while she is at Harfang to show her the mistake she has made and to ask her to repeat the signs, which she can't do.
Although he doesn't physically appear in Underland, the mention of Aslan "recreates" him for the Queen of Underland. His "device" also appears on Rilian's shield.
After Caspian dies, Aslan appears to the children in Narnia and brings them back to the mountain.
Aslan weeps over the dead king's body as it lies in the stream.
He commands Eustace to drive a thorn into his paw and allows his blood to fall on Caspian's body.
Caspian embraces Aslan and they rejoice at his resurrection.
Aslan grants Caspian his wish to see Jill and Eustace's world.
He blows the wall between the worlds down and send the children home with the instructions that they may only hurt their enemies—not kill them.
As a parting shot to the bullies and the Head at Experiment House, Aslan turns his back on them, yet allows them to see that he is there.