You might be right about Duck being reluctant to show true romantic feelings to anyone. But it always seems to me that Duck just wants to get in Zadavia's favour in order to get some promotion from her.
I generally think that Zadavia shouldn't be romantically involved with any of the Loonatics too, but i must admit now that i am very curious about her and Tech after seeing "The Music Villain"!
And i was thinking that sig message of yours sounded a wee bit over-threatening too Earth Master.