Well, the first thing to do would be to rescue Ax. It would mean at least Jake, Marco and Tobias, somehow surviving that ramming Kamikaze stunt, some sort of deal and background info on The One and, making no mistake, just plain freeing Ax! That was not an ending our resident Andalite deserved. p-e-r-i-o-d.
But, on a side note, I once read a fanfic on David's deal with Cryak, where he got to pay back on the Animorphs and was really interesting. Wish the person would manifest his/herself and post it here. It was really worth reading.