Both are Marked - Lydia by Hegeria and Malahi by Yara.
The divergence is that Lydia is willing to risk the secret of her being marked and the price of using her powers while Malahi is not.
Both are daughters of men that are or once were in a ruler position that is capable of being removed.
Senator Valerius is specified as being a former Consul by Lucius Cassius when the latter is gloating over the senator's coming death by poisoning. As the events in Celendrial show - the Consul is an elected position.
King Serrick's rule is predicated on him having the support of 7 of the 12 high lords of Mudamora.
Both are adept at politics and reading others
Malahi in particularly takes to the actions like a duck to water
Lydia does not actually care for the wheeling and dealing but her ability to read Malahi and Hacken is testament to her ability in the arena.
Both are at the very least besotted with Killian Calorian.
Malahi is jealous and possessive of Killian's company.
Lydia is willing to let Killian go if that is what he wants.
