Notes

book eight: in the aftermath of Karai's mutation, the whole family sets out to look for her. Leo and donnie split up into two teams and they take turns going on long, boring patrols for a while (days? weeks?) before they finally find karai. trapping her is another matter entirely, and then it takes a long time for donnie to make a retromutagen, because he says stockman was experimenting with the mutagen and he doesn't know what it did to her. meanwhile splinter bonds with karai, and so do all the rest of them, though Leo is kind of afraid to go to her. eventually it's raph who convinces him to see her, and karai calms the heck down and just kind of slithers around the lair, flicking her tongue out at things. she gets along great with everyone, including April once she apologizes. when donnie finally does create the retromutagen, he can't hide the fact that he was able to use his own blood to do so, and he finally has to explain that he's genetically related to splinter while the other turtles aren't. this is. . . kind of a shock to everyone except for splinter, who already knew, and though donnie's worried it'll make things awkward or worse, they're all just like "I mean. . . explains why ur tall as fuck lmao". he does not create a retromutagen, but he comes up with a partial form that allows karai to switch between forms.

book nine: they get a call from Leatherhead, who's been trapped in dimension x. he tells them that the invasion is ready, Mikey hops into dimension x, the others follow (this time Mikey admits he was there alone for months, and the others are actually horrified and sympathetic). anyway, they let Mikey take the lead, they rescue Leatherhead, they blow up the factory, they go home to prepare and tell the others what's going on. donnie and Leo get into a huge fight about the best way to handle this while the others watch, shocked, but eventually they agree to a compromise: they'll prepare to make a last stand, but then they book it. so April tells her dad to get out of the city, and he goes out to the farmhouse to prepare for their arrival, and donnie goes with casey to explain to his dad and little sister what's going on, and his dad is obviously freaked out (and the sister thinks donnie is the coolest thing ever, and demands he pick her up, and refuses to come down for like twenty minutes). Casey's dad eventually agrees to leave and says that they'll go to Casey's grandparents' place further south, and tries to convince casey to come, but casey says that he's been fighting alongside the turtles for months now and that he has to defend his home. donnie promises to keep casey safe (after trying and failing to convince casey to go) and the dad reluctantly agrees. they give Casey's dad April's dad's number and explain about the farmhouse, casey promises to stay in touch, he has a tearful goodbye, and then they go back to the lair, so that donnie can begin making weapons of war.

book ten: the invasion comes about two weeks after book nine. donnie has barely slept in all this time. all of the mutants in New York city have been preparing, the turtles, April, and casey have been training with splinter practically nonstop, and donnie's enlisted everyone's help to make weapons, and it's a verifiable army of every bit of experimental tech he's ever created, low-key. they of course have metalhead, and with the mutagen karai found in book eight he makes a bunch more flash freeze bombs. he makes rocket launchers, works with casey to upgrade his armor and tasers into actual weaponry, builds a laser sword, adds a second holster across his shell for a tech bo he's built. they're all just kind of in awe because damn donnie? Mikey says that donnie's kind of a super villain, and donnie doesn't argue. so like before, it's April who starts the invasion when she brings irma to the lair, the lair is destroyed, splinter stays to hold down the fort. raph, casey, and karai are out, Leo gets separated from the others in the tunnels, and donnie is injured. donnie calls everyone and tells them to meet at April's apartment. they go, and then Leo comes flying in through the window. casey takes the partywagon back to a manhole cover to keep him safe, meanwhile the others manage to hold the foot at bay, then attack Kraang prime. then they get a call from casey saying that splinter was fighting shredder in the sewers and was injured (but casey saved him! love this little trash man) so now they've got two injured teammates, they escape Kraang prime, and they start driving out of the city, toward the farm house. someone says that the plan worked. someone else says that it still feels like they lost.