Lieutenant Madelyn Adelaide (IPA(key) /mæd'ə'lɪn æd'leɪd/), nicknamed Maddie Addie (IPA(key) /mæd'i æd'i/), is a member of the Basitin army. She snuck onto Eric's ship, The Na'Rella, between chapters thirteen and fourteen. Maddie was the cause of a fire which was blamed on Mike and Evals. She is also the daughter of King Adelaide.
Madelyn has a very up-beat and positive attitude, but is not as mature as her rank suggests, she is more like a teenage girl than a lieutenant in many ways, but in chapter 12, page 556, she can be seen defending Keith in a mature and focused manner. She tends to be very naive as well as curious, and doesn't understand the best way to handle non-combat situations very well. Also, despite her great ability for stealth, she appears to be very clumsy.
Additionally, Madelyn is extremely clever. Taking advantage of Flora's Motherly protectiveness when she escaped from the brig on the Na'Rella. She told Flora that Eric told her the only way he would let her out was if she undressed and then demonstrated groping motions with her hands. Later, when Flora affirms that she'll protect her from Eric (because her story pretty much matches Flora's expectations of Eric), she hugs Flora and smirks, implying to the reader that her story was a complicated but sly falsehood.
It is possible that she has a crush on Keith, as she defended him multiple times and helped him in different situations. Although this could just be her following orders.