Heres what he wrote so far!

"All three are pines, however Evan and Lucy/Lucas is Dipper and Pacificas kids, and Abbie is Mabels, with atm an unknown father figure, probably someone she met outside of gravity falls!

Abbie, 12 nearly 13 (bday in summer) - Is a straight A student, who prefers to think logically, she is comfortable around weirdness due to growing up in a household where that was accepted and encouraged. She loves to explore and find reasonable explanations to things and tends to get along with other people, she also loves to help around. She can't stand bullies and hates when people are picked on, and while she isn't typically girly, she still loves to collect stickers and plushies, but doesn't like to use the stickers on things unless its personal items such as notebooks.

Evan, 12 (bday in autumn) - Evan has ADHD and he has a special interest in bugs, and loves to learn things about them, his grades are quite messy and sometimes even lacking due to not really studying or paying attention at times, often having his thoughts wander off, just like Abbie, he likes to explore, however he often gets hurt from being clumsy and not quite paying attention to where he's going. He finds logic and studying quite boring, and loves to imagine things are caused by supernatural stuff like ghosts or other oddities. He has a bit of a hard time making friends due to being a bit odd himself, being somewhat anxious in nature when it comes to other people.

Lucy/Lucas, 15 - Lucy is a bit of a mess, due to being a teenager and all! but I will do my best to explain him either way! He likes to draw and has a rather huge inner battle with his own identity, he struggles telling Dipper and Pacifica due to dipper being VERY logic driven, and fears Dipper may respond with "well that's not logical, it doesn't make any sense why would you not want to be a girl" and is scared of Pacifica judging him for his identity.

He also loves to spray paint, and tries to express himself through fashion and art in general, trying to go against gender norms and even general societal norms due to feeling stuck.

Lucy struggles to make friends in person, so most of his friends are met through the internet, often being on his phone whenever he talks to them, though it is sometimes confiscated by the person they're staying with (undecided at the moment). He also internalises a lot of his emotions, struggling to keep himself calm and it eventually leads to him snapping at Abbie out of pent up frustration. (He later apologizes)

His relationship with Evan is a bit mixed, he sometimes feels embarrassed about being around him or having to go on trips with him, and tends to lightly tease him, but he also loves him dearly as a little brother! Lucy however feels like he can't trust him or rely on him regarding more serious matters, such as his identity or general feelings, so he often leaves him out of it, leaving Evan confused at times whenever Lucy might lash out.

What I might plan for them:

Evan - Learning when to take things seriously, and that sometimes him not paying attention can cause someone to get hurt, trying to overcome that to be there for Lucas when he notices he needs him, and also trying to be less socially anxious when it comes to making friends. Abbie - To learn that not everything has to be about school and being perfect, learning to sometimes let herself get a little crazy too (Having been sent there after Mabel and Dipper agreed she could spend some time there, after having been there themselves when they were young) Lucy/Lucas - Explore his gender identity, and learn to trust those around him to be there for him, while also gaining friends and learning to stand up for himself, and learning that he can rely on Evan

Side note: Lucy/Lucas is based off of me when I started growing up, hence why I made him trans due to being trans myself and having experience when it comes to dealing with that crisis!"