Here are some references for Selena and Zephyr! (Still working on an updated full body shot for both, so bare with me please.)
And I kind of imagined her legs would look a bit like a cross between these two designs. (Special thanks to @TenguHarley for the chibi version)
She has water, wind, and storm powers if you want to use that in your drawing.
Again, thanks to @TenguHarley for this take on him.
He has wind, electric, and plant powers if you want to use those. (He also "smokes" peppermint candy canes!)
And here's his pet plant Snapdragon if you want to incorporate him in some way as well.
Thanks! Can't wait to see them! Will get to work on Tarrow right away!