The Yeerk does not attempt to cuddle, but it doesn't flee? Progress is still not clear just by looking at the Yeerk.

"Do we have any clever ideas to test this besides allowing the Yeerk to infest one of us?"

"Uh, sometimes I can get people to not react to like pain? But I'd be a lot less confident about that working in an alien, and a lot less confident about it working when I'm not getting good feedback - I'd expect this to be way easier being able to talk to them."

"Now, there's an idea."

"I thought we agreed not to involve the Animorphs too directly? They seem to want to stay far away from all of this."

"If morphing a Yeerk will allow us to prevent several convoluted plans which are much less likely to succeed, I think it's well worth talking to teenagers."

"You can't become a Yeerk, Nereus, but the Animorphs should be able to. Do you think watching two Yeerks interact would help your power work, or is it just you communicating that does it?"

"I'm unsure exactly how much my power helps me with reading people and also unsure how much it can change it's, like, dictionary of body language? If my power's able to change what it's doing I'd expect seeing interactions would help quicken that. And that'd just help feedback, not making my main Master power work quicker."

"Fine. We'll wait a little longer, just in case you can make more progress, and then I'll...let it in."

He nods.

He goes back to trying to befriend the Yeerk with hand motions.

Until eventually, it's time for Derek to be infested.

They won't gag him- the house is isolated enough, and Derek is just a regular human- but they will tie him to a chair. Deaton and Nereus will deal with him if the Yeerk somehow breaks free.

Dr. Deaton takes the Yeerk in his hands, and brings it up to Derek's ear...

...where it proceeds to burrow in.

Nereus is smiling and friendly and definitely not the bad guy here, and all that's directed at the Yeerk -

"Isn't this a nice surprise. Is this an elaborate rescue attempt? I'm flattered."

"It's a bit rude not to introduce yourself, don't you think? My name is Alan Deaton, but you already know that."

"I'm Nereus Uzun. Bit new around here."

"It would be really rude of me to say 'Derek King', wouldn't it? Nice to meet you properly, Nereus. Your previous method of communication was somewhat disorienting. This is much better."

"Nice to meet you! And this's better for me, too. Do you have something you prefer being called?"

"Pettar 867. So, I take it that you're intending to help fight off our invasion?"

"I want everyone to - have what they need to be happy, or content, or - in their preferred state, I guess. Yeerks and humans included."

"That's a shame. Everyone being happy might just be impossible, no matter how charming you are."

"Well, as many people as possible, then, until I get enough power I can make everyone happy."

"...charming. Do you want a defector?"

"I won't force anyone to make that kind of choice, but - I could definitely use the help, if you're offering."