Some facts about tm!Isha:
I can't reveal yet how Isha joins the main group, because it's heavy spoilers.
She's 6 years old by Act 5. She was prematurely born during the Hexgates Incident (by Act 4).
She was born with a speech impediment, she can't articulate words, just make some low noises like her canon counterpart.
Isha has Arcane talents of psychic type. She uses it to communicate with her family and close friends. For everyone else, she uses sign language.
To differentiate her foster moms when talking to/about them, Isha calls Jinx as "momix" and Zeri as "momiz". Meanwhile, she calls Ekko as "papi".
Jinx makes an Aurelion Sol plush for Isha soon as she adopts her.
Contrary to her foster parents, Isha has more affinity with biology than with engineering.
Isha is often gifted with new tools and devices to study biology; most of them are created by her foster parents.
Smolder was initially tasked to be a bodyguard for Isha, but they ended up becoming best friends. He's her right hand during studies, often helping to approach animals or to protect her from them.
Isha and Smolder have a "Lilo and Stitch" dynamic, but Isha is Stitch, and Smolder is Lilo.