Hidden Depths: Cassandra wins a poetry contest at the age of 8, showing to be highly intelligent and precocious child. She's also the most passionate about her Uncle Jed's decision to claim their custody against their will, whereas James' revolt is more reserved.
I Lied: A non-villainous example: Jed promised James and Cassandra that he'd respect their choice to live with him or with the Ingalls, but after Charles informs him they decided for the latter, he declares that even though he wanted to give the impression that he'd give them a choice, he'll claim their custody despite their deciding otherwise.
Incurable Cough of Death: Jed's coughing turns out to be tuberculosis, which makes him realize he can't raise his nephew and niece and give up on his plans.
Rags to Riches: Jed Cooper got a lucky strike and went from a penniless prospector to a rich man with enough money "for two lifetimes", a big fancy house full of servants, and that's what motivates him to seek James and Cassandra's custody.
Reality Subtext: Cassandra's poem in-universe, is full of subtext abiut her experiences after losing her parents and being adopted by the Ingalls.
Secretly Selfish: Jed claims to be thinking about what's best for James and Cassandra, but in the end, he realizes he was only thinking about not being alone and wasn't respecting their decision to stay with the Ingalls.
Uncle Pennybags: Uncle Jed is pretty lax and generous with his money, buying James and Cassandra new clothes and making a point to buy some for all the other Ingalls children to make things even, paying Doc Baker a handsome bonus upon being examinated by him and donating a good amount to the local church. It probably helps that he's on the twilight of his life when he gets rich, and doesn't seem to have much more to do with his fortune in the years to come.
