Fatten rhymes with:
batten, batton, bratten, bratton, caton, catton, craton, flaten, flatten, gatten, gatton, grattan, gratton, hattan, hatten, hatton, latin, laton, manhattan, matton, mchatton, patane, paton, patten, patton, platen, platten, satin, slaton, slatten, slatton, staten, staton, statton, stratton, vanpatten
Fatten sounds like:
fadden, faden, fadiman, fathom, fatima, fatimah, fiefdom, fifteen, fithian, fitton, foodtown, footman, futon