The twins try to behave normally with their father or his pod person, whichever the person who calls them is, for a value of "normally" that involves adamantly continuing to want nothing to do with the Sharing.
And sometimes crying and refusing to tell Renée what's wrong.
School proceeds. No one's grades see more than a minor downturn as a result of all the alien business.
Andi and Robin play music. Andi's getting pretty good on the drums, although her teacher moves away and she has to hunt up another one, who she sticks with for four lessons before deciding to go self-taught.
Bella tightens up her cipher. It began as a letter substitution and since then has evolved to include plenty of personal shorthand - she turns the ratio of shorthand to straightforward letters up as far as she can and still read the thing herself. She abbreviates, she leaves out spaces, she names things in roundabout ways, she refers to things many notebooks ago that she can find easily that anyone else could spend hours hunting for, if she has to record names she finds ways to describe the spelling without ever placing all of the characters in sequence. Maybe the aliens have super-cryptanalysis and super-OCR and can eat her notebooks in one bite and know everything they know; but maybe not, and maybe if she's careful enough she'll look like she's writing her paranoid diary and not like she's taking notes on the quiet invasion.
Trouble comes over a lot. He stays over a lot. Renée has a quiet conversation about him with Bella, in which Bella is vague, pretends ignorance, suggests that maybe he just likes it here, maybe his folks are allergic to gluten and won't eat his baked goods? Renée leaves it alone.
May begins.
He staggers.
<Yes. I am dying,> he replies.
She peeks a little harder.
She whispers to the others, "This isn't the same kind. Trouble looks okay."
And then everyone gets a picture of -
A greenish-gray slug, large for a slug but easily pocket-sized.
<They need hosts. They enter through the ear. Without them they are almost powerless, but when they become Controllers - when they wrap around a host brain and take over their thoughts and actions - they are dangerous. They prefer cooperation. They do not need it. We had hoped to stop them, but soon they will be here to obliterate all trace of me and my ship.>
"Talk about pod people," mutters Trouble. "So what are you warning us for? How do we know who to spill to? A bunch of kids aren't gonna stop an alien invasion by themselves."
<I...> The alien turns all four eyes towards Trouble again, even as the others approach. <I may be able to give you some small advantage. It may help. If you go into my ship you will find a blue box, very plain.>
"How many Yeerks are there? How do you understand English? How can we identify Controllers if we're not sure? Can we get Yeerks out of people? What about the other aliens with all the blades? Are there more of you coming to help? What powers can you give us?"
<There are many millions of Yeerks. And they can breed quickly when there are hosts for them. On this planet - I do not know, but tens of thousands, at least. Controllers can mimic their hosts perfectly if they wish, but Yeerks must leave their hosts once every -> He pauses to make some kind of calculation. <Three Earth days, to go into a Yeerk pool and feed on Kandrona rays, from their home sun or an engineered duplicate. Longer than that and they begin to starve.> He pauses again, main eyes shutting briefly, perhaps in pain. <If you have seen a bladed alien that was not my kind it was probably a Hork-Bajir. They are peaceful of themselves, but their world fell years ago and are now all infested by Yeerks. More Andalites like myself may come to help here but I know not when. And -> He holds his hand out for the blue box.
<I can, if you are willing -> His stalk eyes crane upward, scan the sky. <I can give you the power to morph. Any animal you can touch and concentrate on will be yours to become. The Yeerks do not have this technology. There are limits, but it may help you.>
<It does work. I do not have the strength to morph in this condition; I am dying. Will you take the power?>