She's not staying to witness. Callie is already gone, as is Stiles.

Scott watches from behind a half-constructed wall.

The Blade ship hovers in the air above an abandoned earthmover. As it descends, the earthmover disintegrates just before they would have made contact. The ship settles in the newly-cleared space. 

A door opens in the side. 

Assorted humans watch with dismay.

<Visser Three,> says the Andalite, thick with vitriol.

As if on cue, a figure appears in the doorway, silhouetted against the light coming from inside the ship. 

As the figure begins to move down a ramp to the ground, and their eyes adjust, the form of this new player is revealed... 

Visser Three is an Andalite! 

Rowan has so many questions.

<Visser Three is the only Andalite-Controller,> the Andalite offers, though apparently not to Visser Three.

He waits.

Following behind the Visser come several other aliens.

The first few to leap to the ground look like walking armories, or particularly insane knife enthusiasts, with blade-like horns projecting from their wrists, elbows, knees, tails and foreheads. Each one carries an unfamiliar weapon around the size and approximate shape of a pistol. 

Behind them crawl what look like giant centipedes, far larger than a grown man, with hungry-looking mouths surrounded by tiny, vicious teeth. 

The aliens spread out to surround the Andalite and his ship, weapons pointing both inwards and outwards. 

<Hork-Bajir Controllers,> says the Andalite.

<The Hork-Bajir are a good people, despite their fearsome looks. But they have been enslaved by the Yeerks. Each of them now carries a Yeerk in his head. They are to be pitied.>

Allison isn't giving a pitying look. A mixture of fear and grief, maybe.

She doesn't know how to say anything to him, so she doesn't. She watches.

Of the others, he only says:

<Taxxons. Taxxons are evil.>

This probably isn't the time for a debate about the ethics of dismissing an entire species as evil. They do look kind of gross, but that's not the same thing. He can ask Allison later if she knows anything more detailed, or he can tell Rowan is going to want to find out for herself. 

Visser Three stalks over to the fallen Andalite, stopping just outside the reach of his tail-blade. They look so alike, it's difficult to tell them apart at first: the same blue fur, the same stalk-eyes turning to peer in every direction, the same mouthless face. The same wicked-looking tail, lashing behind him in an indecipherable expression of emotion. 

<Well, well,> he says, broadcasting his thought-speech to everyone who can see him. 

<What have we here?> 

<Visser Three,> he says, 'voice' thick with righteous anger- and pain.

<How astute.> His 'tone' is dry as dust. 

<Your name, of course, is unimportant. You are dying, and there is no-one left to mourn you. Tell me, brave Andalite - how does it feel to know that you have failed?>

<I have not failed, Visser. As long as there are Andalites, you will not succeed.>

<As long as there are Andalites, hmm?> the Visser echoes. 

<Oh, but there are none. Not close enough to make a difference. You are the very last Andalite in this sector of space, and soon there will be none at all to hinder my conquest of Earth.> 

He pauses to enjoy the reaction to this statement. 

<We will stop you. This planet will never belong to the Yeerks.>

<There is an excellent human saying...> Visser Three muses.

<Ah, yes. 'You and what army?' Your Dome ship has been shot down; I saw it fall myself. The closest Andalite fleet is months of travel away. By the time they arrive, this planet and its people will be mine.>

<You know nothing, Visser. They will come.>

The Andalite's tail blade whips through the air- towards his own neck.

The nearest Hork-Bajir startle at the sudden movement and make ready to fire on the downed Andalite. Visser Three takes a step back before he realises exactly what his defeated enemy is doing. 

He could attempt to intervene, catch the tail with his own. He does not. 

The Andalite dies, tail blade slicing through his own throat.

He sends a final message to the human observers: the sense of peace found in tending to his garibah. He sings to it, silently, as his brother watches on, and he knows love and true happiness.

The Andalite dies. 

Allison has too much self-control to cry, when they're this close to the abomination.

She can't actually stop the tears, but she can be quiet.