More rambling thoughts on the AU where Geto defects and takes the twins but doesn't kill his parents or the whole village:
+ He's away when Haibara and Nanami go on the temple mission. He hears about Yu being in really bad shape and so close to death that he might not make it. It's a few hours later when he finds the twins and that's the last drop. So he defects thinking that Yu died, never once looking back or reaching out to confirm or see how everyone else was doing.
+ When he eventually comes back, he and Gojo get into a heated argument. Gojo mentions Haibara and Geto gets upset, saying something along the lines of, "don't you dare taint his memory," and that's when Gojo realizes that Geto doesn't know that, through some miracle (by the name of Shoko Ieiri), Haibara is alive - he can't work as a sorcerer anymore but he became a counselor and works with the kids at the school.
+ After the argument, once they've reached a truce of sorts, Geto asks about Haibara, wanting to meet him but not sure if he'll be well-received (or if he'll get another fractured cheekbone). Gojo gives him Haibara's contact info, letting him know that, out of everyone, Yu was the one that blamed him the least for leaving and staying away. In fact, he stopped both Gojo and Nanami from trying to find Geto, saying that, if he wanted to reach out or return, he should do so on his own terms.
+ Geto messages Yu after leaving Gojo and Nanami's place. Haibara is with Nanami at the time, trying to keep him from getting drunk in the middle of the day (Nanami always goes to Haibara when he's distraught and he can't go to Go for whatever reason). Nanami is angry that Geto is reaching out to Haibara and ends up leaving. Haibara doesn't follow him but sends a message to Higuruma, figuring Nanami will end up at the older man's office or at the bar they frequent.
+ Haibara agrees to meet with Geto the following day. He talks to Higuruma about it over dinner that night (they're living together), and Higuruma agrees to go with Haibara so he can introduce him to Geto (after talking to him alone first).
+ Nanami ends up going to Shoko's. She knows that Geto is back thru Gojo, and is miffed that he (Geto) hasn't reached out to her yet so she joins Nanami in his anger. He passes out on her couch and she calls Gojo so he can pick him up. When he gets there, they talk about Geto, about why he's back and what he wants. Gojo explains as best as he can but she can tell that he's still torn about it.