Sendak chooses you as a mate and takes you aboard his flagship to be with him but he has to make a stop at every biologically active planet so you can examine the plants (especially the mosses) and fungi to see if you need to add them to your collection. By the end of the fic, the whole fleet is just a spacefaring arboretum.
My dream life right there tbh. All the alien plants! Explaining to Sendak how this moss definitely doesn't look like the 20 other ones I have collected already and it needs to come with us on the ship. He acts annoyed but would never say I have to leave something behind. ("Fine, take the fungi, even though you already have 16 that look exactly the same, but hurry up. We have to conquer a planet one galaxy over and Zarkon is getting impatient.") There is a greenhouse but eventually there is a bit of everything growing all around the ship. We save a lot of energy tho because of a bioluminescent lichen that got loose and replaced all the artificial lighting.
~I'm saving this for later because I definitely have to write that fic at some point now XD ~